FAA R

1
FAA RD Dual Flow Inerting System Ivor
Thomas Chief Scientific and Technical Advisor to
the FAA, Fuel System Design
Oct 30th, 2002 ivor.thomas_at_faa.gov
2
Why Reduced Flammability?

• Some tanks on some airplanes heated by nearby
  systems,
• These tanks are the ones involved with last three
  accidents
• FAA considers that tank safety level required
  needs both improved ignition prevention AND
  reduced flammability

3
ARAC FTIHWG

• Industry Study group established in 2000
• To examine inerting systems and make
  recommendations to FAA on future rule making
• Examine various means of supplying inert gas
• Develop cost and operational data

4
ARAC FTIHWG Report

• Inerting not practical because
• No Bleed Air Available
• No Power to run needed compressor
• Complicated distribution system in tank
• Unreliable
• Expensive
• FAA should continue inerting studies

5
FAA Work Since ARAC Report

• Established Bleed Air was available in needed
  quantities but at lower pressures that thought
  needed for Air Separation Technology
• Flow needed for Inerting System approximately 1
  to 2 of bleed flow available
• Pressure adequate for most cases, descent still
  corner design point

6
FAA Work Since ARAC Report

• Testing to establish O2 level needed for inerting
  system
• Adequate inerting obtained with approximately 12
  O2 versus 9-10 previously thought needed

7
(No Transcript)
8
FAA Work Since ARAC Report

• Performance Analysis and subsequent testing
  showed Air Separation Technology would work at
  low pressures, 10 to 40 psig versus 50 to 100
  psig used commercially

9
ASM (Air Separation Module)
10
Recent Significant Progress

• 747 scale model and actual airplane test
• Showed that complex distribution manifold in tank
  not needed
• Simple single line into one bay was much more
  efficient than complex manifold

11
(No Transcript)
12
Recent Significant Progress

• Scale Model Testing
• Tests using a ¼ scale model have been shown to be
  very cost effective and highly representative of
  the full scale airplane.
• Scale model tests have confirmed simple
  distribution system efficacy
• Scale model being used for climb/dive tests of
  system

13
(No Transcript)
14
(No Transcript)
15
Variable flow inerting concepts

• With the results of the bleed system and ASM
  performance, FAA developed several concepts of
  inerting all centered on sizing the system so the
  tank would be inert at touch down, but allowing
  the tank to breath in air in the early part of
  the descent

16
Dual Flow Inerting System

• Use of low flow high purity mode in climb and
  cruise coupled with a high flow, low purity mode
  for descent provides virtually full time
  inerting, without running on the ground.
• Simple system eliminates compressor, cooling fan,
  only moving parts are shutoff valves and a
  temperature regulator

17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
Dual Orifice, Long flight- 200 minutes cruise
duration
Peak due to fuel burn on TO and early climb
22
Initial Conclusions

• Benefits of this approach
• Very Simple system, no compressor
• No ground running needed
• High reliability Only moving parts are cooling
  flow modulating valve, plus shut off valves, plus
  flow controller (Regulator or two position
  orifice)
• Low weight 50 lb manifold to tank (737/A320
  size Center Tank)
• Minimum impact on airplane

23
(No Transcript)
24
Work In progress

• Working with Boeing to develop flight test of the
  dual flow system in the winter of 2002/2003
• Working with Other OEMs on application of
  concept to other airplanes.
• New Spot Amendment to SFAR 88 allows the use of
  inerting as part of an alternate means of
  compliance

25
Summary

• Simple Dual Flow Inerting System shows great
  potential for use in commercial airplanes.