Composite and Administration Aluminum Wing Tank ... · November 20, 2008 Test Apparatus -...
Transcript of Composite and Administration Aluminum Wing Tank ... · November 20, 2008 Test Apparatus -...
0Federal AviationAdministration 0
Composite Wing Tank Flammability November 20, 2008
Composite and Aluminum Wing Tank Flammability Comparison Testing
Steve SummerWilliam CavageFederal Aviation AdministrationFire Safety Branch
Federal AviationAdministration
International Aircraft Systems Fire Protection Working GroupAtlantic City, NJ November 19-20, 2008
1Federal AviationAdministration 1
Composite Wing Tank Flammability November 20, 2008
Outline
Overview
Environmental Chamber Testing• Apparatus• Results
Airflow Induction Test Facility• Apparatus• Results
Planned Work
2Federal AviationAdministration 2
Composite Wing Tank Flammability November 20, 2008
Overview - Background
FAA has released a final rule requiring the reduction of flammability within high risk fuel tanks, with the benchmark being a traditional unheated aluminum wing tank
Next generation aircraft scheduled to enter service in the coming years have composite skin that could change baseline fleet wing tank flammability• Logic assumes composite wings will be more flammable as
they reject heat less effectively compared to aluminum • Could also absorb more heat and/or transfer heat more readily
to the ullage
3Federal AviationAdministration 3
Composite Wing Tank Flammability November 20, 2008
Overview: Wing Tank Flammability Parameters
Flammability Drivers on Ground• Top skin and ullage are heated
from sun• Hot ullage heats top layer of fuel,
causing evaporation of liquid fuel• Bulk fuel temperature however,
remains relatively low
Flammability Drivers In Flight• Decreasing pressure causes
further evaporation of fuel• Cold air flowing over the tank
causes rapid cooling and condensation of fuel vapor in ullage
These concepts were observed during previous testing and reported on recently (see rpt #DOT/FAA/AR-08/8)• The objective is to now compare flammability progression in a
wing fuel tank test article with both aluminum skin and composite skin
4Federal AviationAdministration 4
Composite Wing Tank Flammability November 20, 2008
Test Apparatus - Wing Tank Test Article
Constructed wing tank test article from previous test article• Interchangeable aluminum and composite skin panels on top and
bottom with an aerodynamic nose and tail piece
Tank is vented and has a gas sample port for THC analysis, pressure transducer, and an extensive array of thermocouplesRadiant panel heaters used to heat top surface to simulate ground conditions
5Federal AviationAdministration 5
Composite Wing Tank Flammability November 20, 2008
Test Apparatus - Environmental Chamber Testing
Utilized recently made wing fuel tank test article in altitude chamber to compare Al and Composite Flammability• Performed two identical tests, one with each skin, with 90 deg F
ambient temperature, moderate top heat, and average F.P. fuel• Measured
skin, ullage and fuel temperature progressions over 5-hour period
Environmental Chamber
DAS
Com
puter
TPressureTransducer
CompressedAir
TT
T
T
T
T
T
Vent
Fuel TankTest Article
Altitude THCAnalyzer Gas Sample
Radiant HeaterFuel Storage
T
T
TPump
6Federal AviationAdministration 6
Composite Wing Tank Flammability November 20, 2008
Results - Scale Tank in Altitude Chamber
Testing shows large increases in flammability with composite wing fuel tank skin not seen with aluminum skin when heated from top during ground conditions• Used same heat source, fuel flashpoint, and ambient
temperature on tank with both skin surfaces
When bringing the fuel tank to altitude and dropping the temperature, spike in flammability occurred for both• This is not representative of a wing fuel tank ullage because
flight conditions not simulated• Altitude conditions not simulated with good fidelity (differing
altitude profiles)
7Federal AviationAdministration 7
Composite Wing Tank Flammability November 20, 2008
Altitude Chamber Testing – Flammability Comparison
0
50
100
150
200
250
0 50 100 150 200 250 300
Time (mins)
Tem
pera
ture
(deg
F)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
THC
(% a
s Pr
opan
e)
Top Surface Top Surface Ullage Ullage Fuel Fuel Ambient Ambient Flammability Flammability
Aluminum Skin Composite Skin
Wing Tank Model in Environmental ChamberSimulated Wing Heating - Skin Material Comparison
8Federal AviationAdministration 8
Composite Wing Tank Flammability November 20, 2008
Altitude Chamber Testing – Flammability Comparison
400
420
440
460
480
500
520
540
560
320 330 340 350 360 370 380
Time (mins)
Tem
pera
ture
(deg
R)
0
2
4
6
8
10
12
14
16
Pres
sure
(psi
a) /
THC
(% a
s Pr
opan
e)
Ambient Temp Ambient Temp Ambient Pressure Ambient Pressure Flammability Flammability
Aluminum Skin Composite Skin
Wing Tank Model in Environmental ChamberSimulated Wing Heating - Skin Material Comparison
9Federal AviationAdministration 9
Composite Wing Tank Flammability November 20, 2008
Test Apparatus – Airflow Induction Test Facility
Subsonic induction type, nonreturn design wind tunnel
Induction drive powered by two Pratt & Whitney J-57 engines
10Federal AviationAdministration 10
Composite Wing Tank Flammability November 20, 2008
Test Apparatus – Airflow Induction Test Facility
Test article was mounted in the high speed test section• 5-½ foot in diameter and 16
feet in length.
• Maximum airspeed of approximately 0.9 mach, though with the test article we measured airspeeds of approximately 0.5
11Federal AviationAdministration 11
Composite Wing Tank Flammability November 20, 2008
Test Apparatus – Airflow Induction Test Facility
Due to the design, a simulated altitude (i.e. reduction in pressure) is observed as the airspeed is increased.
12Federal AviationAdministration 12
Composite Wing Tank Flammability November 20, 2008
Test Conditions – Airflow Induction Test Facility
Fuel levels of 40, 60, 80% were examined
Radiant heaters used to heat top surface of tank for 1 hour prior to fueling
• Tests conducted with two different heat settings
Fuel was preconditioned to 90F and transferred into the tank
Heating of tank was continued for 1 hour at which point heaters were removed and wind tunnel was started.
Engines initially run at idle for 5-10 minute warm up period and then taken to 90% throttle
90% throttle position maintained for a period of 30 minutes
Discrete THC sample points were taken throughout testing
13Federal AviationAdministration 13
Composite Wing Tank Flammability November 20, 2008
14Federal AviationAdministration 14
Composite Wing Tank Flammability November 20, 2008
15Federal AviationAdministration 15
Composite Wing Tank Flammability November 20, 2008
16Federal AviationAdministration 16
Composite Wing Tank Flammability November 20, 2008
17Federal AviationAdministration 17
Composite Wing Tank Flammability November 20, 2008
Results – Airflow Induction Facility Tests
• Similar to Environmental Chamber tests, significant increases in both ullage temperature and flammability are observed with composite as compared with aluminum skin• This correlation is evidence that ullage temperature is driver of
flammability
• Fuel temperature increase is also observed, but not as severe
• When aluminum tank is heated sufficiently, and the starting temperature and flammability values are equivalent, the two tanks behave in a very similar manner
18Federal AviationAdministration 18
Composite Wing Tank Flammability November 20, 2008
Planned Work
Some cold weather tests with Aluminum tank will be conducted during the fall/winter months
Composite panels will be painted a white/grey color to examine change in heat rejection
We will first examine effects in lab comparing temperature effects of painted to unpainted panelFollowing this, both panels will be installed on tank and testing will be repeated in the spring/summer months
19Federal AviationAdministration 19
Composite Wing Tank Flammability November 20, 2008
Planned Work
A6 composite wing obtained from China Lake in FY 07 will be utilized in further testing this summer
Preliminary plans are to place it on the ramp next to 737 and monitor tank temperatures and THC progression under varying conditions.
Federal AviationAdministration 19
Composite Wing Tank Flammability November 20, 2008