'RD-AiB 648 A STUDY OF 61RD INGESTIONS INTOYLARGE H IGH BYPASS RATIO I/i

TECHNICAL CENTER ATLANTIC CIT. G FRINGS MARTUBN 8ICRT.U EEA RITO O SITO

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iMICROCOPY RESOLUTION TS HR

,"l NATIONAL BUREAU OF STANDARDS- 1963-A

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A Study of Bird Ingestions into

Large High Bypass Ratio TurbineAircraft Engines

Gary Frings

March 1983

Interim Report

This document is available to the U.S. publicthrough the National Technical InformationService, Springfield, Virginia 22161.

DTICcwMA27 1983

L&J US Department of Transportaton S."m.J kFdwda Aviation Admlnhstvaffia

LL_ Technical Center EAtlantic City Airport, N.J. 08405

' , 040. -I._.

NOTICE

This document is disseminated under the sponsorship ofthe Department of Transportation in the interest ofinformation exchange. The United States Governmentassumes no liability for the contents or use thereof.

The United States Government does not endorse productsor manufacturers. Trade or manufacturer's names appearherein solely because they are considered essential tothe object of this report.

4

DISCLAIMER NOTICE

THIS DOCUMENT IS BEST QUALITYPRACTICABLE. THE COPY FURNISHEDTO DTIC CONTAINED A SIGNIFICANTNUMBER OF PAGES WHICH DO NOTREPRODUCE LEGIBLY.

Technical Report Documentation Page

1. Repo,t No. 2 Go e-.r... Acces.on No. 3. Recipient's Catalog No.

DOT/FAA/CT-82/144 _. . _

4. Title and Subt,tle S. Report nlote

March 1983

A STUDY OF BIRD INGESTIONS INTO LARGE HIGH BYPASS 6. Pe,forming Organizaton CedeRATIO TURBINE AIRCRAFT ENGINES ACT-320

7_ _ _ _ _ _ __ 8. Performing Organization Report No.7 Autl, or s

Gary Frings9. Performrig Organization Name and Address 10. Work Unit No. (TRAIS)

kederal Aviation Administration DOT/FAA/CT-82/144

Technical Center II Contract or Grant No.

Atlantic City Airport, New Jersey U8405 182-320-IU013. Type of Report and Period Covered

12. Sponsoring Agency Name and Address

Federal Aviation Administration Interim

Technical Center May 1981 - April 1982

Atlantic City Airport, New Jersey 08405 14. Sponsoring Agency Code

15 Supplementary Notes

In order to acquire the data contained herein, contracts were awarded by the FAA

Technical Center to the Pratt and Whitney Aircratt Group, General Electric Company

" and Rolls-Royce, Incorporated.

16. Abstract

SA 1-year study has been conducted to document the numbers, weights, and species of

birds being ingested into large high bypass ratio aircratt turbine engines. This

study will continue into a second year. This interim report presents the findings

to date .

".

17. Key Words 18. Ostribution Statement

Bird Ingestion Fan Biades Document is available to the U.S. publicCF6, RBMI1, JT9U birds through the National Technical InformationRevenue Service Service, Springflield, Virginia 22161

Turbine Engines,High Bypass Ratio

19. Security Class,. (of ths report) 20. Securty Class,f. (of thins page i 21. No. of Pages 22. Price

nclassitied Unclassitied 51

Form DOT F 1700.7 (872) Reproductton of completed page authorized 8 '

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TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY vi

INTRODUCTION 1

Objective 1

Background 1

DISCUSSION 2

Worldwide Exposures 2

Airports 4

Engine Ingestions 4

ANALYSIS 17

OBSERVAT IONS 26

APPENDICES

A - Airport IdentifiersB - Statistical Procedure

C - World Map: Bird Ingestion Locations, First Year

D - Bird Ingestion Data Base, First Year

Accession For

NTIS CRA&IDTIC TABUnan-iouncedJUrtificatio

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LIST OF ILLUSTRATIONS

Figure Page

I Exposure Criteria 3

2 Frequency Versus Airports 5

3 Frequency by Month for Total Events 8

4 Frequency by Month for Aircraft 1 8

5 Frequezcy by Month for Aircraft 2 9

6 Frequency by Month for Aircraft 3 9

7 Frequency by Month for Aircraft 4 10

8 Frequency by Month for Engine Model 1 10

9 Frequency by Month for Engine Model 2 11

10 Frequency by Month for Engine Model 3 11

11 Worldwide Bird Ingestion Rates by Aircraft Type 12

12 Frequency Versus Phase of Flight 13

13 Worldwide Bird Weights 15

* 14 Frequency by Month for Multiple Engine Ingestions 16

15 Frequency by Month for Multiple Birds per Engine 17

16 Bird Ingestion Rates 18

17 United States Versus Foreign Multiple Engine Ingestion Rates 19

18 United States Versus Foreign Ingestion Rates 20

19 U.S./Foreign Ingestion at or Below a Given Weight 21

20 Ingestion Rate Versus Airport Operations (Wide-Body Only) 23

21 Bird Weight, Number Per Event and Engine Failure Distribution 25

iv

_. 77 7.

LIST OF TABLES

Table Page

I Bird Ingestion Events, Geographical Distribution 4

2 Bird Strike Reporting Format 6

3 One Year Worldwide Bird Ingestion Summary 7

4 Operational Distribution 12

5 Bird Species, United States 14

6 Bird Species, Foreign 14

7 Bird Weight (in Ounces) Summary 16

8 Bird Ingestion Rates 18

9 Airport Wide-Body Ingestion Rates 22

1 10 Bird Ingestion Summary 24

v

EXECUTIVE SUMMARY

An investigation was initiated by the Federal Aviation Administration (FAA) Tech-*. nical Center in May 1981 to determine the numbers, weight, and species ot birds

which are being ingested into large high bypass ratio turbine aircraft engines on aworldwide basis and what damage, if any, resulted. This interim report presents asummary of the first year's data. Continuation into a second year is currently inprogress. A final report covering both years' data will be issued during the firstquarter of fiscal year (FY) 1984.

-. This report is limited to large high bypass ratio turbine aircraft engines whichexperienced revenue service during the first year of this study. Therefore, only

, bird ingestions into Pratt and Whitney's (PWA) JT9D, General Electric's (GE) CF6,and Rolls-Royce's (RR) RB211 type engines are included. It is anticipated, duringthe second year of this study, that bird ingestion data will become available forthe GE CF6-80A, RR RB211-535 and GE CMF56-2 engines as used on the B77, B757,and reengined DC8-70 series, respectively. The total number ot wide-body aircraft(DCIO, LI011, A300, and B147) active during this tirst year's effort was 1,256.

. These aircratt accounted tor approximately 1.2 million operations.

These aircraft experienced 289 engine ingestion events during the initial contract* period, May 1961 through April 1982. The FAA is continuing this data gathering

ettort tor one more year in order to minimize questions of statistical uncertaintyand trend veritication. Limited analysis of the data is included in this interimreport.

The following summary highlights the data contained in this report:

1. Airlines reporting events 63

2. Airports involved 883. Total events 289

4. hngine damage, minor and/or major 1885. Multiple engine ingestions per aircraft 116. MuLtiple bird ingestions per engine 137. Takeoft and climb phase events 43%

8. Approach and landing phase events 28%* 9. Most commonly ingested bird species, Gull

United States1U. Most commonly ingested bird species, Kite, Gull

Foreign11. Average bird weight, United States 37 ounces12. Average bird weight, Foreign 25 ounces

Analysis of the tirst year's data indicated that the engine tailed in I/ of the188 cases where engine damage occurred. Twelve of these failures occurred at birdweights of 20 ounces or less, and eight failures involved more than one bird perengine.

Preliminary observations relative to the first year's data are: (1) The firstyear's data sample is considered too small to form conclusions, (2) The bird weightversus engine tailure trend is inconsistent in many cases, (3) United States andforeign data sets are not tatistically similar, and (4) the approach and landingphase of flight should also be considered in all data analysis.

vi

INTRODUCTION

OBJECTIVE.

The purpose of this investigation is to determine the numbers, weight, and speciesof birds which are ingested into large high bypass ratio turbine aircraft enginesduring service operation on a worldwide basis and what damage, if any, resulted.This validated data base will be used to determine if amendment of existing stan-dards is warranted.

_BACKG ROUND.

National Transportation Safety Board (NTSB) Recommendation A-76-64 was issuedApril 1. 1976, as a result of an aircraft accident involving a rejected takeoffafter "a number of large birds" were ingested into one of the engines. Thisrecommendation stated in part.

"Amend 14 CFR 33.77 to increase the maximum number of birds in thevarious size categories required to be ingested into turbine engineswith large inlets. These increased numbers and sizes should be con-sistent with the birds ingested during service experience of these

engines." (Class III - Longer Term Follow-up)

In response to the Safety Board's subsequent inquiry of July 30, 1980, the FAA on*October 30, 1980, summarized the status of the work addressing the recommendation

made by NTSB. The FAA had made several examinations of NTSB, FAA, and industryengine records to determine the numbers and weights of birds being ingested intoturbine engines with large inlets. These engines entered airline service early in1969. A study of available records was also made by an Ad-Hoc Committee of theAerospace Industries Association of America, Inc., in 1978. All of these industryand government efforts show available records do not provide the informationnecessary to enable FAA to make a decision concerning revision of the weights andnumbers of birds required to be ingested for engine type certification.

The FAA acknowledged the need for better data relating to the number and weightsof birds being ingested in service operation. Because normal reporting activitywas not providing sufficient information of this kind, the FAA initiated a specialproject at the FAA Technical Center. This project is limited to engine birdingestions being encountered on high bypass ratio turbine aircraft engines duringworldwide service operations.

Completeness of the data and the reliability of data sources are major consid-erations of any effort. In order to achieve the desired valid data base, the FAATechnical Center deemed the following elements essential:

o Worldwide consideration of datao Familiarity with the engine design criteriao Proven expertise and prior experience on engine foreign

object ingestion interpretationo Standardized reporting

o Minimum impact on the operational fieeto Proven expertise in bird identificationo Airline cooperation and understanding of need

.°I

o Quick responseo Report of all engine bird ingestions

Among others manufacturing of large high bypass ratio turbine aircraft engines isconducted by Pratt and Whitney Aircraft, General Electric Company, and Rolls RoyceInc. The FAA determined that the most effective approach to encompass the essen-tial elements was to have each of these engine manufacturers investigate the enginebird ingestion incidents which occurred on their respective engines. This courseof action maximizes the benefit of the engine manufacturer's expertise in damagetolerance assessment and their worldwide service organizations. Thus the informa-tion required for this study was obtained by the manufactureres of high bypassratio turbine aircraft engines with the cooperation of the Air Transport Associ-ation of Amercia (ATA) and the International Air Transport Association (IATA) andtheir member airlines. Standardized bird identification was achieved by eachengine manufacturer by utilizing the services, whenever possible, of a recognizedornithologist.

DISCUSSION

WORLDWIDE EXPOSURES.

The raw data received from each of the engine contractors are encoded prior toinclusion into the Technical Center's data system. The three engine contractors,Pratt and Whitney Aircraft Groups (JT9D), General Electric Company (CF6), Rolls-Royce Inc. (RB211) and four airframe manufacturers of wide-body jet aircraft,Boeing (B747), McDonnell Douglas (DC10), Lockheed (LIOII) and Airbus Industrie(A300) - were arbitrarily assigned coding of I through 3 for the engine identifierand 1 through 4 for the airframe identifier. This coding is not necessarily in theorder shown.

To understand the magnitude of the bird ingestion problem, it was necessary todetermine the numbers of aircraft and engines which were exposed, on a worldwide

* basis, to potential bird strikes. Figure la shows that a total of 1,256 aircraft* were operational during the first year of this effort. Of the 526 type I aircraft,

408 are powered by engine model 1, 86 are powered by engine model 2 and 32 arepowered by engine model 3. Of the 344 type 2 aircraft, 300 are powered by enginemodel 2 and 44 are powered by engine model 1. All 220 type 3 aircraft are poweredby engine model 3. Of the 166 type 4 aircraft, 158 are powered by engine model 2,and 8 are powered by engine model 1. Alternatively, this data can be discussedfrom the engine viewpoint instead of the aircraft viewpoint. Of the 4.128 engineswhich were involved in this study, 1,780 are engine model 1 1,560 are engine model2, and 788 are engine model 3.

To compare and contrast the bird ingestion rates of the various aircraft types, itwas necessary to determine the total number of operations conducted during thestudy period. An "operation", as used in this study, is contrary to normal FAApractice and is defined as either a takeoff or a landing, but not both. Therefore,a flight, for example. from airport "A" to airport "B" is counted as one operation,one revenue departure, or one takeoff. The main tool used in determining numbersof operations was the Official Airline Guide (OAG) computer tapes which are updated

. every month. These tapes are used to identify the airline schedules and provide*" valuable data such as, aircraft type. departure and arrival airports, frequencey of

2

flight, and domestic/foreign operations. To validate the accuracy of the OAGoperational data, engine manufacturer's data were obtained as a cross-check. Their

operational count was 5.7 percent higher (69,000 operations) than the OAG data.Further analysis revealed that 57,00u of these operations pertained to the type 1aircratt which is extensively utilized for treighter operations and, therefore, notalways included in OAG data. The operational data reported in this study reflectthese increased operations. Approximately 1.2 million operations occurred duringthe study period. Aircraft type I had 411,000 operations, aircraft type 2 had

316,(0U operations, aircraft type 3 had 263,000 operations; and type 4 had 214,000operations (figure Ib). These data were used in the analysis section of thisreport to construct ingestion rates.

MAY 1, 1981 - APRIL 30, 1982(5261

500 500,000

400 400,000

(3441

< 300 < 300,000-•U

(220)c

200 - 200,000

(166)

100 100,000-

2 3 4 1 2 3

(a) AIRCRAFT TYPE (b) AIRCRAFT TYPE

FIx;URE 1. EXPOSURE CRITERIA

3

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AIRPORTS.

From the OAG tapes it was determined that 384 airports worldwide accommodated the

wide-body aircratt types studied. Fifty-eight of these airports are located in the

United States (U.S.) and 326 are foreign. During this study, engine bird inges-

tions were experienced at L4 known U.S. and 74 known foreign airports. Figure 2

depicts 88 airports, with the number of events reported at each airport. The

tabulation of "U.S. Only" data has been included in figure 2. The acronym iden-

tifiers for these 88 airports are listed in appendix A. It should be noted that

an identifier of "XXX" is shown. This identifier denotes occurrences at unknown

airports. Eighty-five such events occurred. Traces of a bird ingestion which arefound on the engines during maintenance, post- or preflight-inspections make the

location of the ingestion unknown.

Although the specific airport where the bird ingestion occurred may not be known,

it is possible, in many cases, to determine whether the ingestion occurred in the

United States or in a foreign country. By "extrapolating" data, such as operations

between United States or foreign city pairs and operator route structures, it is

possible to reduce the number of unknown bird ingestion locations from 85 to 33 by

allocating 45 ingestion events into the foreign category and 7 into the U.S. cate-"'!i gory (table 1).

TABLE I. BIRD INGESTION EVENTS GEOGRAPHICAL DISTRIBUTION

U.S. Foreign Worldwide

Total Ingestions - - 289

Validated Locations 37 167

Extrapolated Locations 7 45 -

Unknown Locations - - 33

Mi nimum 44 212

• .(validated plus extrapolated)

Maximum 77 245

(minimum plus unknown)

" ENGINE INGESTIONS.

During the course of this study no attempts were made to compare the relative

merits or shortcomings among the engine models or aircraft types.

Table 2 lists the type of information which was reported by the engine manufac-turers tor each bird lngest ion event. It was not possible in all cases to obtain

all the information desired (see appendix D). For example, when the local time of

the ingestion Is unknown, the column entry is listed as "0000." Likewise, when the

* bird number or weight is unknown, the column entry is "0." In all other cases, anunknown quantity is listed as "UNK." In those cases where a particular columnentry does not apply, the term "N/A" is entered. An example of this might be a

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. case where a bird ingestion has occurred but no damage resulted, thereftore, theS1"in-tlight Shutdown, "Pilot Action, and *Significant Reason" columns would all*have an -N/A- entry.

The Event Number" of appendix D are computer generated and sequential by date ofbird ingestion occurrence. An "Event", as used in this report, refers to an air-cratt bird ingestion occurrence. Computer program tormat limitations have by

"" neccessity forced some of the entries of appendix D to be grammatically incorrect,* such as the hyphenating of certain words.

TABLE 2. BIRD STRIKE REPORTING FORMAT

1. Date2. Local Time3. Aircraft Type

4. Engine type

* 5. Engine Position

6. Operatorl. Airport

6. Phase ot Flight9. Weather

10. Damage11. Power Loss or Reduction (yes or no)12. Conta'ned Damage (yes or no)13. In-flight Shutdown (yes or no, it yes - reason)14. Was the bird seen?

15. Bird Species16. Bird Number11. Bird Weight1b. Pilot Action (Aborted takeott or air turn back)19. Was this a signiticant event? (i.e., multiple engine ingestion,

multiple birds per engine, transverse fan blade fracture, involuntary powerloss, actual or suspected engine related airworthiness effects).

20. Manutacturer's Event Number21. Remarks

'Table 3 summarizes the worldwide bird ingestion events of the tirst year. A totalof 289 bird ingestion events were reported worldwide; 278 of these events involvedonly one engine per ingestion. Eleven events involved two or more engines. The

- term damage, as used in this report, refers to any type of damage which theengine sustained as a result ot the bird ingestion. This may range from minordamage such as a nicked or bent tan blade to extensive damage. A listing of bird

-" ingestions by aircraft type and engine model is also shown in table 3.

*- It has been possible to validate the bird weights in JU percent (145 cases) of the- bird ingestion events. This high percentage ot known bird weights results from the- tact that all three engine manufacturers have contracted to send bird debris which

is collected trom the engine to the Smithsonian Institution for identification

4 and analysis by an ornithologist. It should be noted here that upon engine impactmany birds literally "explode" and very little ot the bird remains for identitica-tion. hlowever, sutticient bird debris - such as feather down and portions offeathers - remain attached to the engine crevices to allow not only identification

6

of the species but also sex and whether the bird was mature or immature. Thisinformation, together with location of strike and time of year, allows the orni-thologist to determine a range of weights for the bird(s). The bird weightsreported in this study are the midpoints of the range of weights as reported bythe ornithologist.

TABLE 3. ONE YEAR WORLDWIDE BIRD INGESTION SUMMARY

Events 289Aircraft #1 119Aircraft #2 54

Aircraft #3 41Aircraft #4 75Engine Model itl 87Engine Model i2 146Engine Model #3 56Ingestion with Damage 188Bird Weights 145

Multiple Engine 11Multiple Birds Per Engine 13

Figure 3 depicts the bird ingestion events by month for the tirst year for allaircraft types. Although there appears to be a considerable increase in the numberut engine bird ingestions in the late summer and early fall, it is too early to

- determine the cause of these increases (increased aircraft operations, birdmigration habits, etc.).

Figures 4 through / present the same information by aircraft type, while figures 8,9, and 10 present the information by engine model. Except for minor perturbations,the trend is similar for all the figures.

A necessary step in understanding the engine bird ingestion phenomena is to comparethe ingestions ot the four aircraft types. In doing so, one must address theproblem in terms ot rates since the number of ingestions and operations variesconsiderably among the aircraft types. The resultant ingestion rates do nottake into account such intluential factors as: number ot engines and theirlocation, route structure, operational procedures, and other factors. The numberof bird ingestions per 10,000 operations is a convenient number which has been

utilized by the industry to make this comparison. Using the total number of opera-tions tor each aircraft type, as shown in figure Ib, and the total number of birdingestions occurring on each aircraft type, as shown in figures 4 through /, theengine bird ingestion rate per 10,000 operations was constructed for each aircrafttype. Figure 11 graphically depicts the results. The worldwide rates are 2.9,

* 1.7, 1.b and 3.5 for aircraft types I through 4, respectively. The worldwideaverage ingestion rate considering all aircraft types as a unit is 2.4. It isoutside the scope of this interim report to attempt a qualitative explanation of

* .these variations in rates.

. .

60

° .'"50

40-

30

" 30WORLD WIDE

20-

10 1-

MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR81 81 aI 81 e1 61 81 a1 82 62 62 62

FIGURE 3. FREQUENCY BY MONTH FOR TOTAL EVENTS

20

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10 WORLD WIDE

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MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APRal ei 81 81 81 61 81 81 82 82 82 82

FIGURE 4. FREQUENCY BY MONTH FOR AIRCRAFT 1

8

20

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WORLD WIDE

i LLI ,II1,MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

81 81 81 81 81 81 81 81 82 82 82 82

FIGURE 5. FREQUENCY BY MONTH FOR AIRCRAFT 2

15

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WORLD WIDE

MAY JLN JUL AUG SEP OCT NOV DEC JAN FEB MAR APRK'81 81 81 81 81 81 81 81 82 82 82 82

I.,-

k ILURE 6. FRE(4UENC( BY MONTH FOR AIRCRAFT 3

% 9

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WORLD WIDE5MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

81 81 81 81 8l 81 81 81 82 82 82 82

FIGURE 7. FREQUENCY BY MONTH FOR AIRCRAFT 4

20 r-

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MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

81 81 81 81 81 81 81 81 82 82 82 82

FIGURE 8. FRE(C't, CY BY MONTII FOR ENGINE ,ODEL 1

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MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR81 81 al al81 61 81 81 82 82 82 82

FIGURE 9. FREQUENCY BY MONTH FOR ENGINE MODEL 2

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81 81 81 81 81 81 81 81 82 82 82 82

FIGLRE 10. FREQUENCY BY >MONT11 FOR ENGINE MODEL 3

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. FIGURE 11. WORLDWIDE BIRD INGESTION RATES BY AIRCRAFT TYPE

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The data of f igure I1I addresses the worldwide ingestion rates. At this point it• became apparent that the relationship between worldwide, U.S. , and foreign opera-

:tions must be established for comparison purposes. The OAG data tapes were used

""to determine this operational distribution. The results of this analysis areSshown in table 4. In table 4, the "Fleet Total" figures may not be the sum of the

:individual aircraft types, due to rounding off of the numbers. Attempts weremade to construct ingestion rates for individual aircraft types in U.S. and foreign

-ioperations. This approach was abandoned because of the inability to determine". into which category, U.S. or foreign, the "Unknown" location events should beSplacea. A bias would have been introduced into either the U.S. or foreign in-

gestion rates had these "Unknown" location events been incorporated.

" TABLE 4. OPERATIONAL DISTRIBUTION

• Ai rcraf t•Type United States (U.S.) Foreign Worldwide

1 114,000 (28%) + 297,000 (72%) = 411,000

2 151,¢00 (48%) + 164,000 (52%) = 316,0003 125,000 (48%) + 137,000 (52%) = 263,000

4 35,000 (16%) + 179,000 (84%) = 214,000

FLEET To)TAL 426,000 (35%) + 777,000 (65%) =1,203,000

•NOTE. ()represent percent ot worldwide total by type

12

It is important to understand during what portion of a typical flight a birdingestion is likely to occur. Of the 289 events which were studied during thefirst year, 43 percent of the ingestions occurred during the takeoff and climbphase of flight, while 28 percent occurred during the aproach and landing phases.With few exceptions, such as descent and taxi, the remaining phases of flight(approximately 25 percent) were unknown. This is again attributable to those caseswhich were discovered during maintenance or post/preflight inspections.

Figure 12 graphically depicts the phases of flight where the ingestions occurred.The phase of flight data used to generate this graph is that which was reported bythe engine manufacturers who ultimately received it from the operator of theaircraft. It is recognized that phase of flight definitions vary considerably inthe industry, however, the data is a compilation from many operators and it isassumed normal data scatter would tend to mitigate any bias in phase of tlightdefinitions.

120 -

100

oWORLD WIDE

60

40

20 II!Au

TO CLIMB CRUISE DESCNT APPRCH LANDING TAXI UNK

FIGURE 12. FREQUENCY VS PHASE OF FLIGHT

I

i~i .13

Tables 5 and 6 list the types of birds ingested during this study which have beenidentified. In the United States, the most frequently ingested birds are the gullswhich account for 18 of the 28 known birds (out of 37 events). The two mostfrequently ingested foreign bird species are kites and gulls. Together, these twogroups account for half of the foreign ingestions (38 out of 76 birds) in thosecases where the bird is known. The range of weights of gulls is between 1 and 4pounds, while kites average between 1 1/2 to 2 1/2 pounds.

TABLE 5. BIRD TYPES, UNITED STATES

Type of Bird Number of Birds

GULL .............................................. 18HerringRing-billedGreat Black-backLaughinigUndetermined

CANADA GOOSE ........................................ 3MALLARD DUCK ........................................ 2PIGEON .............................................. 2HAWK ................................................ 2

Red-tailedRough-legged

COWBIRD ............................................. 1

TABLE 6. BIRD TYPES, FOREIGN

Type of Bird Number of Birds Type of Bird Number of Birds

KITES 20 DUSKY THRUSH ............. 1Black ROLLER ................... 1Red MEADOWLARK ............... 1

GULLS ................... 18 CORNCRAKE ............... 1Herring LAPWING .................. 1Great Black-backed FRANCOLIN ................ 1Black-tailed THICK KNEE............... 1

* Black-headed ROOK ..................... 1Ring-billed RED-TAILED HAWK.......... IGray-head CANADA GOOSE ............. 1

" Common HERON .................... IUnde te rmi ned WHITE VULTURE ............ 1

PIGEONS .................. 5 INDIAN VULTURE ........... 1DOVES.................... 4 AFRICAN STORK............ 1CROWS .................... 3

- GODWITS.................. 3PLOVERS.................. 3

. DUCKS .................... 2OWLS ..................... 2BATS ..................... 2*

*Included with birds because of flight behavior

14

As mentioned, it has been possible to validate the weight of the birds in 145 cases

out of the 289 events which occurred. Twenty-eight birds were ingested in the

United States while 105 birds were ingested outside the United States (foreign).

it was not possible to determine the location for 12 bird ingestion cases. Figure

13 depicts the worldwide bird weight distribution. For the foreign data, there

were 5 cases where the bird ingestion weight was equal to or greater than 4 pounds

(64 ounces). In the United States, this occurred in 3 cases.

300

ca. 25S.' .I::. . 20

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5 10 15 20 25 30 35 40 45 50 55 60 64+ABOVE30 (a) BIRD WEIGHT (OUNCES) - FOREIGN LOCATIONS

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- 10 15 20 25 30 36 40 45 50 55 60 S4+ABOVE

co 30 (b) BIRD WEIGHT (OUNCES) - U.S. LOCATIONS

25

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2 10

5 10 15 20 25 30 35 40 45 50 55 60 64+ABOVE(C) BIRD WEIGHT (OUNCES) - UNKNOWN LOCATIONS

FIGURE 13. WORLDWIDE BIRD WEIGHTS

15

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Table 7 summarizes the bird weight distribution. The most likely weight is thatweight which occurs the most frequently. The weight at which an equal number ofweights occur, both above and below it, is called the median weight. Examination

of table 7 shows a decidedly different distribution of weights most noticeably the

smaller size of the foreign versus U. S. birds.

TABLE 7. BIRD WEIGHT (IN OUNCES) SUMMARY

Foreign (+) U.S. (+) Unknown () Worldwide

Number 105 28 12 145

Average Weight 25 37 16 25

Most Likely Weight 24 40 4-8-11 II

Median Weight 17 40 11 11

Of the 289 bird ingestion events which were reported during the first year of this* study, there were 11 events in which two or more engines per aircraft ingested at

least one bird each (multiple engine ingestion), and 13 events wherein two or morebirds were ingested into one engine (multiple birds per engine). Although thesetwo types of ingestions can be considered independent events (one can occur withoutthe other), during this study 3 events were reported wherein both phenomena occur-red simultaneously. Figures 14 and 15 show the distribution of these events during

the study period.

10

0cc

%5

: WORLD WIDE

I -

•MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

81 81 81 81 81 81 81 81 82 82 82 82

;. FIGURE 14. FRF(J GENCY BY MONTH FOR MUILTIPLE ENG;INE INGESTIONS

|16

10

'U

.'U

* 0

. 2 sWORLD WIDEZ

MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

81 81 81 81 81 81 81 81 82 82 82 82

FIGURE 15. FREQUENCY BY MONTH FOR MULTIPLE BIRDS PER ENGINE

The first year's data emphasized that in some instances it was difficult to assess- the exact number or birds ingested into an engine. To minimize this problem, a

meeting ot the three engine manufacturers' representatives and FAA Technical Centerpersonnel was held to discuss "bird printing" methodology. As a result, it isanticipated, during the second year's effort ot this study, that the reportingof multiple bird ingestions per engine events will be more consistent. This infor-mation is necessary since the present engine certification criteria are based, inpart, on a fixed quantity of birds which are required to be ingested into anengine. NTSB recommendation, A-76-64, specified, in part, that "the numbers andsizes (ot birds which are ingested during certification) should be consistent withinservice experience."

ANALYS IS

*To examine certain hypotheses, statistical and analytical examinations of the datahave been conducted. The results of these examinations are presented in the

* OBSERVATILONS section ot this interim report.

The question has been asked Are the U.S. and foreign rates similar for both thesingle and multiple engine ingestions?" Table 8, which combines the data from

• table 1 and table 4, presents the bird ingestion rates for U.S., foreign, and*worldwide areas. Figure 16 graphically illustrates the data of table 8.

17

TABLE 8. BIRD INGESTION RATES

Ingestion Events Operations Rate (Ingestions/1O,O00 Ops.)

Worldwide 289 1,203,000 2.40

Foreign*Minimum 212 777,000 2.73*Maximum 245 777,000 3.15

U.S.*Minimum 44 426,000 1.03*Maximum 77 426,000 1.81

* See Table I.

4: EXTRAPOLATED DATA

VALIDATED DATA

- 3

I-

* gU

2

U.S. FOREIGN WORLD WIDE 82-144-16

FIGURE 16. BIRD INGESTION RATES

To examine the question posed, a statistical test-of-hypotheses procedure was

employed. The procedure is explained in appendix B. Examining the multiple engineingestion events first (figure 14), the data reveals that two U.S. and nine foreignevents occurred. Two events per 426,000 operations (see table 8) yields a U.S.

multiple ingestion rate of 4.69 X 10-2 per 10,000 operations.

* The 9 foreign multiple ingestions in 777,000 operations (see table 8) yields aforeign multiple ingestion rate of 1.16 X 10-1 per 10,000 operations. The upper

and lower bounds of the 95 percent confidence interval about the foreign multipleengine ingestion data have values of 2.25 X 10-1 and 5 X 10-2 respectively. Sincethe U.S. ingestion rate is not encompassed by the 95 percent confidence interval of

*the foreign data, one may conclude that the U.S. and foreign multiple engine inges-tion rates are statistsically different. These computations are illustrated infigure 17.

18

9 -

8-

%q 7

5

4

3

2

10

* 0 9

7C

* U.S.

4 \ 95% CONFIDENCE INTERVAL

03

* CD

-

NOTEBASED UPON 2 U.S. EVENTS9 FOREIGN EVENTS

10-2 -

FIGURE 17. MULTIPLE ENGINE INGESTIONS, U.S. VERSUS FOREIGN

A similar test was conducted for the rate of U.S. versus foreign ingestion events

(table 1). The calculate.! U.S. validated ingestion rate is 0.87 per 10,000 opera-

tions. Using the described statistical procedure, the confidence interval for the

U.S. ingestion rate ranges between 0.61 and 1.20 per 10,000 operations. The

foreign validated ingestion rate is 2.15 ingestions per 10,000 operations. Since

the foreign ingestion rate does not lie within the 95 percent confidence interval

of the U.S. ingestion rate, (figure 18) the conclusion is that the U.S. and foreign

rates of bird ingestions per 10,000 operations are, in fact, statisticallydifferent.

119

3.0

25

" FOREIGN.0

0

9L 95°° CONFIDENCE INTERVAL

"' 1.0LU.S.

BASED UPON 37 U.S. EVENTS

0.5 167 FOREIGN EVENTS

0

FIGURE 18. INGESTION RATES, U.S. VERSUS FOREIGN

Attempts have been initiated to determine why the U.S. and foreign ingestion rates

are different, but the results to date are inconclusive. As mentioned previously.such factors as operator route structure, operational procedures, and others maycontribute to this difference, but these parameters are difficult to assess.

Figure 19 illustrates the differences between the U.S. and foreign bird ingestion

occurrences. The data used to construct figure 19 consists of 28 U.S. events and.- 105 foreign events for which the bird weights and locations are known (figure 13).

Both sets of weight data were grouped into quarter pound increments to determinewhat percentage of the weights occurred at or below a specific weight. Beyond 48ounces (3 pounds) the data became too sparse to be meaningful. The figure alsopresents the 95 percent confidence interval of the U.S. weights at the discretequarter pound increments. As an aid to the reader, the discrete quarter pound

increments of the U.S. and foreign distributions are connected by a smooth line butit must be remembered that this analysis is valid only at the discrete quarterpound increments. It is interesting to observe that the foreign data set is

intersected by a U.S. confidence interval only at the extremely low and highweights. The inference is that although U.S. bird weights are generally higher

than foreign bird weights (table 7) the probability of the bird ingestion being of

the same weight is about the same only for the extremes of the weight data.However, between approximately three-quarters of a pound and 3 pounds, the data

' sets are different. For example, a bird weight of approximately one pound or lessis ingested 50 percent of the time in the foreign environment, however, the U.S.data suggests that for the same 50 percent of the time a 2 1/2 pound or less bird

will be ingested.

*. 20

79 7' " '

,-, 100 I

FOREIGN

U.S.

80-I-

* -~P

, oI-

"'0; NOTE

95% CONFIDENCE INTERVALal 40-

' I-

20-

I 64 & ABOVE

0 10 20 30 140 so 60BIRD WEIGHT (OUNCES)

FIGURE 19. U.S./FOREIGN INGESTION AT OR BELOW A GIVEN WEIGHT

The question of which airports, where high bypass ratio turbine engine aircraftoperations are conducted, experience the greatest number of ingestions is partiallyanswered in table 9. Figure 20 illustrates table 9 data. It is not possible tocompare the absolute number of ingestion events among airports because of the

diversity in the numbers of operations conducted. Therefore, a comparison of- ingestion rates per 10,000 operations is given. It is apparent, however, that a

calculation of the ingestion rate at an airport which has an extremely low opera-tions count produces an ingestion rate which is subject to considerable statisticaluncertainty. For example, an airport which experiences one bird ingestion in ayear and has only 124 operations (such a case exists), produces an ingestion rateof 80.65 which has such a wide interval of uncertainty associated with it as to

" make it meaningless. In order to avoid such unfair comparisons, table 9 presents*! only those airports at which the operations counts for the aircraft types which

were monitored during this study are at least 10,000. In order not to bias thedata, airports which have had at least 10,000 operations, even though no bird

. ingestions were reported, are included in table 9.

21

.'- ........

io

TABLE 9. AIRPORT WIDE-BODY INGESTION RATES

(10,000 or More Operations)Airport Operations Ingestions Rate Rank

ORY 18454 10 5.42 1BOM 11407 6 5.26 2FCO 12080 5 4.14 3HND 30247 11 3.64 4YYZ 11271 4 3.55 5CDG 19600 6 3.06 6LGA 10639 2 2.91 7LHR 28853 7 2.43 8JFK 53271 11 2.07 9JED 11035 2 1.81 10OSA 25708 4 1.56 11LAX 46058 5 1.09 12ATH 10201 1 0.98 13MIA 31883 3 0.94 14SFO 22762 2 0.88 15ATL 27841 2 0.72 17BKK 16466 1 0.61 18HKG 18438 1 0.54 19BOS 19511 1 0.51 20ORD 35924 1 0.28 21NRT 24008 0 - -

HNL 20007 0 - -

SIN 19224 0 - -

SEA 13777 0 - -SYD 12766 0 - -RUH 11266 0 - -

TPE 10962 0 - -

CTS 10498 0 - -

EWR 10351 0 - -

ANC 10091 0 - -

22

..] ... o --...

10M9-

7

6 BOM* • ORY

* FCO40

SYYz CDG HND3 -LGA R~LHR

0

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. OSA

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- 0.5 - H * BOS

0.4

0.3 -

ORD

0.2

0.1I I I I III II10 15 20 25 30 40 50 60 70 80 90100

OPERATIONS (THOUSANDS!

FIGURE 20. INGESTION RATE VERSUS AIRPORT OPERATIONS (WIDE-BODY ONLY)

23

It has been stated that of the total 289 events which were reported, 188 eventsresulted in some type of damage, whether minor or major. Of these 188 damagingevents it has been determined that 17 of these resulted in engine failure. Forthis study an engine failure is based upon engineering judgement which encompassesmany criteria among which is the engine's ability to attain and/or maintain 50percent thrust. Figure 21 illustrates the number of birds ingested at a specific

- weight range. Each open circle represents an ingestion, each filled-in circle*- represents a resultant engine failure.

An engine failure upon ingestion of a 4-pound or heavier bird is not unexpectedand this occurred in 3 out of the 8 ingestions reported. Similarly, ingestion of8 or more medium size (1 1/2 pound) birds is not unexpected (although no such eventoccurred during the study period). However, 2 ingestions of 8 or more birds werereported in the 1/2 to 3/4 pound category which resulted in engine failure.Significantly, the engine also failed in the 6 remaining ingestions (out of 13total) where 2 or more birds per engine were ingested. Finally, in 12 out of the17 engine failure events the individual bird weight ranged between 1/2 and 1 1/4

* pounds. These observatons are depicted in figure 21. Based upon these obser-vations it becomes apparent that the correlation between bird weight and engine

.. failure is inconsistent in many cases.

Table 10 reviews some of the relationships which have been presented in thisreport.

TABLE 10. BIRD INGESTION SUMMARY

EngineTotal Damaging Failure

Ingestions Ingestions Ingestions(289 Events) (188 Events) (17 Events)

Takeoff+ 43% 56% 75%

Climb

Approach+ 28% 21% 25%

Landing

MultipleBird

Ingestions 13 (5%) 11 (6%) 8 (47%)Per

Engine

MultipleEngine 11 (4%) 5 (3%) 1 (6%)

Ingest ions

24

4 & ABOVE

> 3-3%0

NOTE> 2%-3

00 00 0 ENGINE FAILURE

> 2-2%00 _

> 21/-2A

> 2-2%&,&00__ __ ____

>2 > 143-%

.--

> ~~ 88800 ______ __ __

> 1%-VA2

> 1-1%

> 1

> %1Y:::. ' - 8oooolo

~0-Y4

1 2 3 4 5 6 7 8 OR MORE

NUMBER OF BIRDS PER ENGINE

FIGURE 21. BIRD WEIGHT, NUMBER PER EVENT AND ENGINE FAILURE DISTRIBUTION

'9 25

*- Certain aspects of table 10 warrant further attention:

1. Takeoff and climb phases of flight produce the highest percenta es inall categories.

2. Not withstanding item 1, the approach and landing phases of flight. produce a constant percentage across all three categories of engine ingestions.

3. Multiple bird ingestions per engine occur in a significantly high per-centage of the engine failure events.

4. Multiple engine ingestions do not produce significant percentages (rel-., ative to item 3) in any category (columns).

OBSERVATIONS

Some preliminary observations can be made based upon the first year's data.

1. The first year's data sample is considered too small in most instances to allowconclusions. This was apparent during the statistical analysis of the UnitedStates (U.S.) versus foreign multiple bird ingestion evaluation and also during theairport bird ingestion rate analysis.

2. The bird weight versus engine failure correlation is inconsistent in many casesas evidenced by figure 21. It is outside the scope of this investigation toexplain this inconsistency.

" 3. The U.S. versus foreign engine ingestion rates are not statistically similar.This may be biased by the sample size.

4. The approach and landing phase of flight should also be considered in all birdingestion data analysis since a significant portion of the events occur in thesephases.

26

APPENDIX A

AIRPORT IDENTIFIERSI

I

- '. - - -

APPENDIX A

AIRPORT IDENTIFIERS

ABJ Abidjan, Ivory Coast FCO Rome, Italy, L. Da Vinci Arpt.

AMM Amman, Jordan FEZ Fez, Morocco

AMS Amsterdam, Netherlands FIH Kinshasa, Zaire

ATH Athens, Greece FLL Ft. Lauderdale/Hollywood,

ATL Atlanta, Ga., USA Fla., USA

. BGF Bangui, Cen. African Republic FRA Frankfurt, Republic of Germany

BKK Bangkok, Thailand FUK Fukuoka, Japan

BOD Bordeaux, France GIG Rio de Janeiro, Brazil

BOM Bombay, India (International)BOS Boston, Mass. USA HAM Hamburg, Rep. of Germany

BRU Brussels, Belgium HKG Hong Kong, Hong Kong

BWI Baltimore, MD., USA HND Haneda Airport, Tokyo, JapanCAI Cairo, Arab Rep. of Egypt HYD Hyderabad, IndiaCCU Calcutta, India IAH Houston, Texas, USACDG Paris, France, IST Istanbul, Turkey

Charles De Gaulle Arpt. JED Jeddah, Saudi ArabiaCPH Copenhagen, Denmark JFK John F. Kennedy I-t. Airport,DEL Delhi, India New York, USA

DKR Dakar, Senegal JNB Johannesburg, So. Africa

- DPS Denpasar, Indonesia KAN Kano, NigeriaDUR Durban, South Africa KHI Karachi, PakistanKMQ Komatsu, Japan OKA Okinawa, Ryukyu Is., JapanLAX Los Angeles, CA, USA ORD Chicago, Ill, O'Hare Airport, USA

LCA Larnaca, Cyprus ORY Paris, France, Orly Airport. LGA Laguardia Airport, NY, USA OSA Osaka, Japan: LGW London Eng., Gatwick Airport PEN Penang, Mayalasia

- LHR London Eng.,Heathrow Airport PHL Philadelphia, PA., USALIM Lima, Peru PTY Panama City, Panama Republic

LIS Lisbon, Portugal PUS Pusan, Rep. of Korea

LOS Lagos, Nigeria RST Rochester, Minn., USA

LPA Las Palmas, Canary Is. VCP Sao Paulo, Brazil, Viracopos Airport.- LYS Lyon, France SFO San Francisco, CA, USA

,A- Madras, India SID Sal Island, Cape Verde IS.MEL Melbourne, Australia SNN Shannon, Rep. of IrelandMIA Miami, Fla., USA STR Stuttgart, Rep. of Germany

Mil Milan, Italy SXR Srinagar, India

MNL Manila, Philippines TLS Toulouse, France

- MPL Montpellier, France TLV Tel Aviv-Yafo, IsraelMRS Marseille, France TUN Tunis, Tunesia

MTY Monterrey, Mexico VIE Vienna, AustriaMWH Moses Lake, Wash. USA WLG Wellington, New ZealandNBO Nairobi, Kenya YUL Montreal, Quebec, Canada

NGO Nagoya, Japan YVR Vancouver, Br. Columbia, Canada

NGS Nagasaki, Japan YYZ Toronto, Ontraio, CanadaNIM Niamey, Niger ZRH Zurich, Switzerland

* NKC Nouakchott, Mauritania

-A-I

. .- ,

APPENDIX B

STATISTICAL PROCEDURE

APPENDIX C

WORLD MAP: BIRD INGESTION LOCATIONS, FIRST YEAR

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