JOHN MORTON

PRINCIPAL ENGINEER

SYSTEMS ENGINEERING

BOEING COMMERCIAL AIRPLANES GROUP

S A F E T Y

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Nine months after its launch,

MyBoeingFleet.com is still

in its youth, but it has

welcomed more than 11,000

new users and now receives as many as 800 log-ins per day.

This secure Internet portal has been clearly established as

friendly, fast growing, and full of useful data.

PERSPECTIVE

ROGER NICHOLSON

ASSOCIATE TECHNICAL FELLOW

SERVICE ENGINEERING

BOEING COMMERCIAL AIRPLANES GROUP

BILL ROBERSON

DIRECTOR

EXECUTIVE FLIGHT OPERATIONS

BOEING COMMERCIAL AIRPLANES GROUP

BARB CLAITMANDIRECTOR OF E-BUSINESS COMMERCIAL AVIATION SERVICES BOEING COMMERCIAL AIRPLANES GROUP

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If you havent logged on to youraccount lately, you might want to checkout our latest offerings, released inDecember 2000. Operators can now viewreports summarizing worldwide fleet service history schedule reliability, flighthours, landings, utilization, and length offlight information. We also provide quickaccess to the latest product standards for 707s and for 727 through 777 airplanes.This includes standards for drafting,material, operations, processes, and parts.

MyBoeingFleet also features a site that helps operators manage configuration control of airplane loadable software independently of any hardware. And wecontinue to add more maintenancedocuments to the site daily. For example,operators can now review on line signifi-cant rework to recently delivered Boeingairplanes in their fleet.

Although MyBoeingFleet continues togrow and change, our goal is constant to be your single online source of mainte-nance, engineering, and flight operationsdata. And by giving you exactly the information you need when you need it,well succeed in making it easier for youto do business with us.

Im excited about whats ahead forMyBoeingFleet in 2001. We recently invitedcustomers from a number of airlines to aforum and asked them how they use the web site and what we could do to

improve it. The wealth of feedback wereceived will help drive some usabilitychanges to the site during the year. We also look forward to visiting these customers at their work sites to get evenmore specific data.

Were on track in 2001 to include ouronline spare-parts ordering system in our single log-on and to continue adding moreonline alternatives to hard copy, such as our Data and Services catalog. Making the transition to online documents throughMyBoeingFleet can significantly reduce airline costs associated with distributing,managing, and storing paper documents.At the same time, it improves accessthrough online search capabilities and 24-hour, seven-days-per-week availabilityof data. It also raises quality because documents in the database will have thelatest revisions and updates.

If you havent yet tried MyBoeingFleet,Ill hope you will take a look at what we can offer. You may tour the site fromwww.boeing.com by clicking the cus-tomer logon button and selecting Take a Guest Tour. Or, if you prefer, you maycontact the Boeing Digital Data CustomerSupport by e-mail at DDCS@boeing.comor by telephone at 206-544-9990 Mondaythrough Friday, 6:30 a.m. to 6 p.m. (U.S. Pacific time).

airplane design and maintenance (seeAging Airplane Systems Investigation,Aero no. 7, July 1999), these initiativesinclude improvements to the proceduresused by the flight and cabin crews during a smoke event in the pressurizedarea of the airplane.

ANALYSIS OF PAST SMOKEEVENTS AND REVIEW OF CREWPROCEDURES

Boeing performed an analysis ofreported in-service events that involvedsmoke, fumes, fire, and overheating inthe pressurized areas of its airplanes

An in-flight fire or smoke event is a time-critical situation that demands immediateaction by the flight and cabin crews. Cigarettesaside, any smoke in an airplane is not normal.Crew response must be timely and use available airplane controls and non-normalprocedures.

To help ensure that appropriate steps are taken,the following issues need to be understood:1. Operational consequences and safety

risks of smoke events.2. Analysis of past smoke events and review

of crew procedures.3. Recommended crew action for known and

unknown smoke sources.4. Capabilities for the remainder of the flight.

OPERATIONAL CONSEQUENCES AND SAFETY RISKS OF SMOKE EVENTS

Although most smoke events in the pressurized area of an airplane are resolved and rarely affect continuedsafe flight, landing, or egress, smoke is always a significant issue with operational consequences. Theseconsequences include flight cancellations, flight schedule disruptions, air turnbacks, airplane diversions,declared emergencies, airport emergency equipment

responses, airplane evacuations, accom-modations for displaced passengers,diminished goodwill, and extensiveunscheduled maintenance following non-normal procedures such as overweightlanding inspection, recharging of oxygen,and repacking of escape slides.

Direct crew response to smoke andfumes originating from readily accessibleequipment, referred to as known smoke,is key to minimizing operational consequences. Timely and prudent crewresponse to smoke events of undeterminedorigin, or unknown smoke, minimizesrisks during the remaining flight, landing,and egress.

Based on past smoke events,Boeing and other air transport industryleaders are pursuing initiatives tofurther reduce the likelihood of in-flight smoke. In addition to enhancements to

Engineering design by airplane manufacturers, oversight by regu-lators, and maintenance practicesby operators combine to minimize occurrences of smoke, fumes, and fire in the pressurized areas of airplanes. When smoke does occur, timely and appropriate action by the flight and cabin crewsis imperative. Boeing has analyzed in-service smoke, fumes, and fire events and reviewed airplane systems and crew procedures for its commercial airplane models.

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between November 1992 and June 2000.Data were compiled for each model and included the following: the areaaffected in the pressurized area of theairplane, the smoke source perceived by the flight crew, the smoke sourceidentified by the maintenance crew,the category of the smoke source, theairplane system or equipment involved,the means of detection (typically sight or smell by passengers or crew),and the effect on flight completion.(Note: The term smoke in the precedinglist and in the remainder of this articlerefers to odors, smells, fumes, or

overheating as well as visible smoke.)The smoke events under study were

categorized into three classes: airconditioning, electrical, and material. Air-conditioning smoke events were casesin which incoming bleed air was con-taminated, perhaps from engine oil or contaminated outside air. Electrical eventswere cases in which electrically poweredequipment overheated or emitted smoke orfumes. Material events involved materialthat gave off smoke or fumes such as food burning in an oven, lavatory wasteignited by a discarded cigarette, or spilledchemicals in the cargo compartment.

2

Envir

onm

enta

l con

trol s

yste

m (E

CS)

Flight deck equipmentMaintenance

Galley contents

Fuel/hydraulic leaks

Cargo fumesSmoking materialInlet air

APU

ECS

Engine

Lighti

ng

Wind

ow he

atHe

ater

s

Ente

rtai

nmen

t sys

tem

Electric

al powe

r

Galley

Wiring

No data

Smoke events, November 1992 to June 2000

Electrical, 64%

Air conditioning, 14%

Material, 12%

Smoke sources

Smoke events, November 1992 to June 2000

Ground/maintenance Unknown s

moke

Smoke events with flight crew on board, 72%

Electrical smoke

Air-co

nditio

ning s

moke

Material s

moke

Cargo smoke

System fault no smoke detected

No crew

response data

Smoke events, November 1992 to June 2000

Electrical

Air conditioning

Material70%70%

7%

16%

51%

21%21%

777 747-400 MD-11/DC-10 767 757 737 717/DC-9

15%

64%

14%12%

38%

45%48%

31%

6%

26%

41%

4%4% 4%

Smoke sources

SUMMARY PROFILE OF REPORTED SMOKE EVENTSIN PRESSURIZED AREAS OF THE AIRPLANE

FIGURE

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Figure 1 depicts a summary profile of air-conditioning, electrical, and material smoke events for each airplanemodel included in the study. This formatenables comparison across airplanemodels of the three major smoke sourcecategories. For each model, the numberof events in each source category wasdivided by the total number of smokeevents for that model, yielding the per-centage contributions depicted in theprofile. (Note: The three categories foreach model may not sum to 100 percentbecause of insufficient informationavailable to categorize an event.) Themodels in figure 1 are listed in order of airplane complexity, starting with the most complex on the left. Larger airplanes with more complex systemsshow a predominance of smoke eventsof electrical origin, compared with air-conditioning and material smoke events.

For each airplane model, the air-conditioning, electrical, and material

events were subdivided by airplane system. Figure 2 illustrates such adetailed categorization of smoke eventsources for a representative model. The subcategories within the electricalcategory include systems or functionssuch as environmental control, elec-trical power, galleys, and flight deckequipment. Presenting the smokesources in percentages by airplane system or function allows comparison of multiple models with different fleetsizes, ages, and missions.

Data also were collected on how the crews perceived the in-flight smokeevents on all models. The data weregrouped in a structure similar to theflight crew Quick Reference Handbook(QRH) produced by airplane manufac-turers and operators. Figure 3 showssuch a portrayal for a representativemodel. Most smoke events occurredwith the flight crew on board. For many in-flight events, flight crews took

action consistent with having identifiedthe smoke source, such as removingelectrical power to (i.e., depowering)that equipment. There was a significant number of events in which crew actionssuggest that the smoke source could notbe identified while in flight. For smokeevents in which the flight crew could not determine the smoke source, mostwere subsequently determined by main-tenance crews to be of electrical origin.

RECOMMENDED CREW ACTIONFOR KNOWN AND UNKNOWNSMOKE SOURCES

The Boeing QRH includes proceduralsteps for smoke, fumes, fire of air-conditioning and electrical origin, andsmoke removal. When a flight crew has determined that smoke is of air-conditioning origin, the Boeing QRHprocedure is to isolate the air source,halting the introduction of contaminatedair into the pressurized area of the

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SMOKE EVENT SOURCES FOR A REPRESENTATIVE AIRPLANE MODEL

FIGURE

2

FLIGHT CREW PERCEPTION OF SMOKE SOURCEFOR A REPRESENTATIVE AIRPLANE MODEL

FIGURE

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disruption from a smoke event comesfrom crew training in responding tosmoke, crew familiarity with smoke-clearing procedures, and direct powercontrol to cabin amenities (e.g., anelectrical power cutoff switch at eachgalley location). If the crew cannotconfirm that a persistent onboardsmoke or fire situation is completelyresolved, however, Boeing recommendsthe earliest possible descent, landing,and evacuation of the airplane.

Unknown smoke sources. A crew may not be able to identify a smokesource because of the location of thefailed equipment or because of air circulation throughout the pressurizedcabin. Unknown smoke sources include environmental control systems, equip-ment cooling fans, door heaters,plumbing heaters, avionics equipment,fluorescent lights, and wiring faults.

The serious consequences of com-promised structural integrity, systemfunction, or survivable environment warrant timely and prudent action

by the crew. Review of historical data on the rare fire events that resulted in hull loss indicates that the time from first indication of smoke to an out-of-control situation may be veryshort a matter of minutes. For thisreason, flight crew actions whenresponding to unknown smoke must be timely and appropriate.

QRH procedural steps for address-ing an undetermined electrical smokesource call for the removal of elec-trical power for specific systems notnecessary for safe flight, landing, andegress. This accounts for the majorityof systems with a significant history of in-service smoke events. Also, asdirected by the Boeing QRH non-normal checklist, the crew should plan to land at the nearest suitable airport.

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During the remainder of the flight, thecrew should be alert to any new signs thatsuggest the smoke source and remainmindful of operational functions needed to accomplish the diversion.

Many unknown smoke situations are laterattributed toelectricalsources,

substantiat-ing the posi-tive step ofdepoweringspecificequipmentnot neces-sary for theremainingflight, land-ing, and egress. Flight-critical systems donot have a significant smoke-event history.

CAPABILITIES FOR THE REMAINDER OF THE FLIGHT

QRH procedural steps to remove powerfrom affected equipment must ensure that

airplane. An example of air-conditioningsmoke is from engine oil, followed by ab-normal engine parameters and odor in thecabin and flight deck. Once the crew hasisolated the incoming engine bleed air,continuing fresh air from another sourceshould quickly improve cabin air quality.

When a flight crew determines smokeis of electrical origin, the Boeing QRHprocedure is to depower the affectedequipment. For example, if a flight crew sees smoke from a window-heating element, appropriate action would be to switch off that electrical equipment.An example of known smoke in thecabin would be a flight attendant seeingand smelling smoke from a coffeemaker; after turning off electrical powerto that galley, the smoke stops and subsequent surface temperatures are normal. The key to properly handling a known smoke event is for the crew tobe confident of both the smoke sourceand the effectiveness of removing electrical power.

Known smoke sources. Many smokeevents involve smoke or fumes producedby equipment readily accessible to thecrew. Often, the event source can be iden-tified by direct observation, such as see-ing smoke exiting a piece of equipment,tracing a smell to its strongest location,or feeling an unusually warm surface.

For a known smoke event, confirming

that the situation has been resolved is asimportant as identifying the source. Thesmoke or fumes must dissipate and anyoverheating condition must improve forthe crew to be confident the situation isunder control. Only if the crew can con-fidently identify the smoke source andconfidently ascertain that the condition isunder control should continuation of theflight be considered. Hand-held extin-guishers ought to be at the ready, as thecrew continues monitoring the equip-ment during the remainder of the flight.

Factors to evaluate in deciding whether to continue the planned flight

include the level of confidence in identifying the smoke source, success inextinguishing the source, functionality of the remaining systems, success inremoving cabin smoke, passenger dis-tress, and position of the airplane alongthe intended route. Any combination of these factors may make a diversion or turnback the appropriate choice.

Completing a planned flight has itsadvantages given the significant opera-tional costs of substitute equipment,schedule disruption, potential passengercompensation, and diminished goodwill.The best prospect for minimum

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The following tips are based on the review andanalysis of in-flight smoke events on Boeing air-planes between November 1992 and June 2000:

Although not a serious risk for propagatingfire, several events occurring immediatelybefore or after airplane departure were attributed to engine or auxiliary power unit(APU) maintenance activity during the previous ground leg. Most operators haveground crew procedures for engine or APUruns following maintenance. For an operatorwith concerns in this area, a review of ground procedures that require engine or APU run may be appropriate.

Some known smoke events are directly preventable. Paper may come into contactwith hot lighting, either in the cabin or crew rest areas. Food may be left in an oven or a coffeepot heated while empty.

Smoke or actual fire events have been initiated by repeated circuit breaker resets during ground troubleshooting. Even whenperformed on the ground, circuit breakerresets should be performed cautiously.Important considerations are the numberof reset attempts, cooling time betweenreset attempts, and the stationing of main-tenance crew monitoring for unusualsounds or smell.

A flight crew may be able to identifyunknown smoke as air-conditioning smokebased on subsequent indication. In an air-conditioning smoke event caused byleaking engine oil, the first symptom noticed by the crew may be a burning odorof unknown origin. Subsequent engine indications might clarify an abnormal engine situation, and the correspondingbleed air source can be isolated.

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sufficient system capability remains to accommodate adverse weather, areplanned route, and an approach into anunfamiliar airport. In-service data showthat inordinate depowering of airplanesystems beyond QRH procedures is notlikely to be of benefit in an unknownsmoke situation. Further, such actionwould significantly reduce airplane capa-bilities for the remainder of the flight.

During the study, several depoweringstrategies beyond current procedureswere considered but ultimately not incorporated into the Boeing QRHnon-normal checklists based on a risk-benefit evaluation. The elements of continued safe flight and landing weredetermined according to four safetyrequirements: controlled flight path,controlled airplane energy, navigation,and survivable environment. Conditionsduring the remainder of the flight could necessitate the availability of flightmanagement systemnavigation, autopilot,multiple communica-tion channels, first officers displays,smoke detection, firesuppression, cabinlighting, and electricalpower for removingsmoke.

Exterior lightingillustrates the importantdifference between aprudent crew responseand an inordinatedepowering of airplanesystems during anunknown smoke event.Equipment used for red anti-collisionstrobes includes high-energy compo-nents, such as ahigh-intensity flasher,and is an occasionalsource of smoke in thepressurized area of the

airplane. From this standpoint, using the overhead switch to depower red anti-collision strobes may be beneficialduring an unknown smoke event. Turningoff all exterior lighting, however, wouldbe an overreaction that would increasethe risk of traffic conflict without commensurate likelihood of addressingthe smoke source.

Without complicated troubleshooting-type procedures, it is a practical impos-sibility to depower all potential sourcesof unknown smoke without compro-mising necessary systems. The key todepowering potential unknown smokesources while protecting necessary airplane functions involves balancing aseries of risk assessments. Because theQRH must facilitate timely and prudentcrew action appropriate for a broadrange of scenarios, the QRH procedurescannot resort to a severely depowered

electrical configuration. Boeing QRHprocedures are developed with the under-standing that, at a flight crews discretion,additional action may be taken that isdeemed necessary to ensure safe flight.

If a flight crew considers action beyond the QRH procedures, the actionmust be based on the particular situationand knowledge of airplane system opera-tion. Procedural alternatives that may bereasonable near a familiar airport undervisual meteorological conditions may not be appropriate in adverse weather orunfamiliar surroundings with a com-promised airplane. The crew may also have additional flight deck effects orinformation beyond those explicitly identi-fied in the QRH (e.g., tripped circuitbreakers, synoptic information, or reportsfrom cabin crew) that may assist in identifying the smoke source.

A flight crew in an extreme situationwill benefit from airplane system know-ledge that would be inappropriate todetail in time-criticalprocedures. Forexample, on mostBoeing-designed two-engine airplanes,the right electrical bus powers a higherproportion of non-essential equipment,while the left electri-cal bus powers thehigher proportion of flight-criticalequipment.

The best response to an event ofunknown smoke com-bines use of prudentQRH non-normalchecklists and flightcrew discretion basedon the particularsituation and a thor-ough knowledge ofairplane systems.

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SUMMARY Engineering design by airplane manufacturers, oversight by regulators,

and maintenance practices by operators combine to minimize occur-rences of smoke, fumes, and fire in the pressurized areas of airplanes.

When an in-flight smoke or fire event does occur, it can be a time-critical situation that demands immediate action by the flight and cabincrews.

Crews should follow QRH procedures, which must be structured to allowflight and cabin crews to promptly respond to an in-flight smoke event.

In known smoke events, direct crew response minimizes operational consequences, such as flight cancellations and air turnbacks.

If a crew cannot confirm that persistent onboard smoke or fire has been completely extinguished, Boeing recommends the earliest possible descent, landing, and evacuation of the airplane.

In unknown smoke events, a prudent crew response minimizes risk during remaining flight. Inordinate depowering of airplane systems is notlikely to benefit an unknown smoke situation because such action signifi-cantly reduces airplane capabilities for the remainder of the flight with-out commensurate likelihood of depowering the unknown smoke source.

Many unknown smoke sources are later determined to be electrical,substantiating the positive step of depowering specific equipment notcrucial to the remaining flight, landing, and egress. Historically, flight-critical systems have not significantly contributed to smoke events.

In an extreme situation, a flight crew will benefit from knowledge of airplane systems that would be inappropriate to detail in time-critical QRH procedures.

TIPS ON MINIMIZING SMOKE EVENTS