# Presentation: 233810

## Eliminate Flammable Fuel / Air Vapors in Transport Category Aircraft

##  Fuel Tank Explosions

-  Fuel Tank Explosions

- 346 fatalities since 1989

**Avianca 727, November 1989**

**PAL 737, May 1990**

**TWA 747, July 1996**

## Safety Improvements Wanted

**Safety Improvements Wanted**

-     ...preclude the operation of transport-category airplanes with explosive fuel/air mixtures in the fuel tanks:
- Develop airplane design modifications such as nitrogen-inerting systems and insulation between heat-generating equipment and fuel tanks.  **A-96-174**
- Modify operations to reduce the potential for fuel-air mixtures in the fuel tanks that will preclude explosive fuel-air mixtures in the fuel tank.**  ****A-96-175**                  (Closed - Unacceptable)

## Fuel Tank Explosions a Threat?

- Video of a secondary explosion in a 737 at Okinawa, September 2007

## FAA Actions

- Total design review of all transport airplane fuel systems for potential ignition sources.
- Development of a nitrogen-based flammability reduction system.

**FAA Actions**

## Addressing only ignition sources has proven to be inadequate.

- to current ignition prevention standards.
- SFAR88 process found additional ignition risks.
- After more than 120 airworthiness directives issued,
-    16 _***additional***_*** ***threats were found to require AD action

**Addressing only ignition sources ****has **_***proven***_** to be inadequate.**

## Addressing only ignition sources has proven to be inadequate.

**Short circuit of fuel pump power wires in metal conduit routed through fuel tank.**

**Source of Fuel Tank Ignition****Transmile 727, Bangalore, India**

## FAA Developed Fuel Tank Rulemaking     FAA obtained industry and public input    NTSB did not agree to exclude wing fuel tanks

- The proposed new rule would would require:
- Flammability reduction in
-  Existing fleet
-  Newly manufactured airplanes
-  New designs Establishment of new design standardsNew operating rules for retrofitting existing airplanes

**3,277 airliners**
**total**

## Inerting CWT Helps Wing Tank Flammability

**INERT TANK**

**WING TANK**

**NITROGEN**

**COMMON **
**WING TIP **
**VENT**

- Nitrogen shared at shared wingtip vent box
- Nitrogen is heavier than air
- Extent of cross-venting varies

## New Technology

## Flammability Reduction Systems Work

-   Four airplanes flying since end of 2005
-   Over 30,000 flight hrs at 11 to 13 hrs/day/plane
-   No technical problems or failures
-     Manufacturer and operator: “Non-Issue” technically
-   Fuel cost essentially too small to be measured
-   Test program is resulting in design improvements

## Rule Repeatedly Delayed

-     NPRM Published on 11/23/05

**Rule Repeatedly Delayed**

- DOT Office of Secretary
-     Returned to FAA twice: 8/13-27 and 9/10-25
-     Scheduled to deliver to OMB June 20, 2007
- Publication scheduled for September 2007
- Now scheduled for February 2008

## Cost-Benefit Analysisis the Big Issue

- “We continue to work on the details of the rulemaking action to determine how it can be imposed consistent with our mandate to demonstrate that the additional benefits of this requirement are sufficient to justify its costs.”
- FAA letter of October 23, 2007

## NPRM Benefits Understated

- Fact:  Over 346 deaths since 1989, 541 since 1959
- Fact:  Over 25 fuel tank explosions.
- Using OMB methodology, the FAA excluded:
-  Wing tanks – some benefit reaches wing tanks
-   Indirect benefits – Fire protection in unoccupied areas
-   Deliberate acts
- Benefit apparently based on small number of cases
-   Leaves analysis vulnerable to criticism of individual events

## Costs Were Overstated

- 1998 Industry ARAC Estimate
- $35 Billion

- 2005 FAA NPRM Estimate
- $808 Million

## Fuel Tank Explosions Since TWA 800

**Transall C160R, May 2004**

**Transmile, May 2006**

- Thai Airways, March 2001

## Eliminate Flammable

**Fuel/Air Vapors in Fuel Tanks**

| Timeliness Classification | YELLOW |
| --- | --- |

**Proposed Safety Board Actions**
-  Keep the issue area on Most Wanted List
-  Retain yellow designation:    Acceptable response – progressing slowly