1. March 26-27, 2003 International Aircraft Systems Fire Protection Working Group Phoenix, Az Inerting of a Scale 747SP Center-Wing Fuel Tank During a Typical Commercial Flight Profile William Cavage AAR-440 Fire Safety Research Federal Aviation Administration

2. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Outline Background Model / Instrumentation Test Data –Effect of Holds at 5K Feet –Running System on Ground –Effect of Deposit Schemes –Starting Descent Altitude –Blocking Vent System Dive Port Summary

3. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Background FAA is seeking to improve upon existing fuel tank safety in fleet in the wake of TWA800 air disaster Inerting of fuel tanks could provide significant fuel tank protection. Focus of the testing is to validate the ability of the FAA simplified fuel tank inerting system to inert the CWT of a 747SP during a typical commercial flight profile Use modeling results to validate modeling methods with full-scale data Study inert gas distribution during the commercial mission

4. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Description of Model Quarter-scale model of Boeing 747SP CWT was built from three-quarter inch plywood by scaling drawings from Shepherd report –24% length scale (1.4% Volume) –Spars and spanwise beams simulated with quarter-inch plywood installed in slats with scaled penetration holes –Vent system simulated with PVC tubing plumbed to an aluminum vent channel –Removable lid to allow for model maintenance and modification Model in 6x6x7 altitude chamber Model inerted with manual NEA mixer

5. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Photo of Model

6. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747 SP Bay Diagram with Volume Data

7. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Instrumentation Onboard oxygen analysis system (OBOAS) acquired bay oxygen concentration data –One sample port in each bay –Sample returned to tank through manifold Thermocouple in chamber gave temperature Altitude measured by absolute pressure transducer NEA Flow metered/measured with mass flow controller and oxygen concentration determined with flow through type oxygen analyzer

8. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Onboard Oxygen Analysis System Block Diagram

9. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Altitude Chamber NEA Mixer Oxygen Analyzer Flow Controller Scale Tank Testing Block Diagram DAS Nitrogen Compressed Air NEA Generator Computer T OBOAS Pressure Transducer Sample Return Scale Tank Model

10. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Scope of Testing to Date All testing used same generic flight profile with different cruise times and different holds at 5K feet All testing uses same predicted system performance in terms of NEA flow and purity during above mentioned mission All tests had right side vent system blocked –Some tests had aft port on open vent side also blocked

11. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 OBIGG System Model

12. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Effect of Hold at 5K Feet Baseline case (no hold) repeated with two different hold times –Hold at 5K feet –5 and 10 minute holds Results indicate that holds using high flow mode have little effect on both tank average oxygen concentrations and worst bay oxygen concentrations –System is depositing NEA at approximate oxygen concentration as tank –5-10 minutes not that long to improve distribution for relatively small spread

13. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

14. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

15. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

16. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Effect of Hold at 5K Feet (Cont’d) Ideally like to decrease tank average oxygen concentration before you use high flow mode to improve distribution –Use low flow mode during a hold at 5K feet (lower’s average tank oxygen concentration) –Switch back to high flow for final descent (distributes) Results illustrate this flow methodology improves overall average tank oxygen concentration at touchdown but doesn’t increase in the worst bay oxygen concentration –Using high flow mode to distribute gas has diminishing returns Effect of sample system minimal when checked

17. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

18. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

19. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

20. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Running System After Touchdown Repeated baseline case touchdown data with two tests that run system on ground after touchdown –15 and 30 minutes system run times –one test only sampled beginning and end of ground sit time Running System in Low Flow Mode After Touchdown did little for worst bay oxygen concentration –Gave consistent benefit over time for tank average oxygen Running System in High Flow Mode After Touchdown did decrease bay oxygen concentration spread –Average oxygen concentration changed little –Again, diminishing returns on reducing spread

21. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

22. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

23. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data (High Flow Mode)

24. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Deposit Scheme Comparison Compared running system after touchdown with two different deposit scenarios –Duel deposit method deposits low flow mode in bay 6 and high flow mode in bays 1 and 3 –Multi-deposit method deposits all flow into bay 6 and bay 2 (approximate equal split) –Baseline used low flow mode during 10 minute hold pattern Fancy deposit schemes did little to improve touchdown average or worst bay oxygen concentration –More work needed Repeatability check gave excellent results

25. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

26. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

27. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

28. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Starting Altitude Comparison Compared original baseline descent case (from 39K feet) with two additional starting altitudes (32K and 25K) –Used same altitude profile with different starting point (same descent rates) with no hold –Approximated system performance best possible Results were as expected –Starting altitude will have dramatic effect on resulting average oxygen concentration provided the tank is consistently inert for all cases

29. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

30. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Effect of Blocking Dive Port Existing venting scheme does not give optimal inerting efficiency –Illustrated in constant inerting tests –Would improve by blocking dive port (aft vent port) on open side Repeated baseline test data (no hold) with this venting configuration –No effect on average tank oxygen concentration –Had adverse effect on distribution with 2% higher spike in worst bay and a full 3% greater resulting worst bay oxygen concentration Compared two deposit schemes with this venting config –Use 10 min hold for comparison case –Only small effect observed on bay 1 spike and on result

31. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

32. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

33. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 747SP Scale Fuel Tank Inerting Data

34. Scale Fuel Tank Testing ___________________________________ ISFPWG Meeting - 3/26/03 Scale model data shows FAA inerting methodology sound given the predicted system performance –System could be slightly undersized Using high flow mode only, decent hold buy you very little in terms of average of worst bay oxygen concentrations Running system on ground after touchdown in high flow mode will decrease oxygen concentration spread, but has diminishing returns (when average oxygen concentration is near 12%) More elaborate deposit schemes and system methodologies give relatively small performance benefit, but could improve inerting capability significantly of a marginal system Summary