BOEING 767ABX Air
San Francisco, CA, USA · 2008-06-28·N799AX
What happened
NTSB summary, verbatimThe Safety Board’s full report is available at http://www.ntsb.gov/publictn/A_Acc1.htm. The Aircraft Accident Report number is NTSB/AAR-09/04/SUM. On June 28, 2008, about 2215 Pacific daylight time, an ABX Air Boeing 767-200, N799AX, operating as flight 1611 from San Francisco International Airport, San Francisco, California, experienced a ground fire before engine startup. The captain and the first officer evacuated the airplane through the cockpit windows and were not injured, and the airplane was substantially damaged. The cargo flight was operating under the provisions of 14 Code of Federal Regulations Part 121. At the time of the fire, the airplane was parked near a loading facility, all of the cargo to be transported on the flight had been loaded, and the doors had been shut.
Photographs
4the aircraft, and what the investigators foundPhotographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.
Probable cause
the Board's determinationThe design of the supplemental oxygen system hoses and the lack of positive separation between electrical wiring and electrically conductive oxygen system components. The lack of positive separation allowed a short circuit to breach a combustible oxygen hose, release oxygen, and initiate a fire in the supernumerary compartment that rapidly spread to other areas. Contributing to this accident was the Federal Aviation Administration’s failure to require the installation of nonconductive oxygen hoses after the safety issue concerning conductive hoses was initially identified by Boeing.
Occurrence sequence
3 stepsNTSB coding · CICTT taxonomy- 1 · Standing-engine(s) start-upElectrical system malf/failuredefining event
- 2 · Standing-engine(s) start-upSys/Comp malf/fail (non-power)
- 3 · Standing-engine(s) start-upFire/smoke (non-impact)
Findings
2 causal · 2 contributing- CAUSEAircraft › Aircraft systems › Oxygen system › Passenger oxygen system — Design
- CAUSEOrganizational issues › Development › Selection/certification/testing › Equip certification/testing — FAA/Regulator
- FACTORAircraft › Aircraft systems › Fire protection system › Smoke, detection — Not specified
- FACTOROrganizational issues › Management › Policy/procedure — Operator
Safety recommendations
12 issuedwhat changed because of this accidentTO THE FEDERAL AVIATION ADMINISTRATION: Require operators to replace electrically conductive combustible oxygen hoses with electrically nonconductive hoses so that the internal hose spring cannot be energized.
TO THE FEDERAL AVIATION ADMINISTRATION: Prohibit the use of electrically conductive combustible oxygen hoses unless the conductivity of the hose is an intentional and approved parameter in the design.
TO THE FEDERAL AVIATION ADMINISTRATION: Formalize the airworthiness directive process so that, when an aircraft manufacturer or other source identifies an airworthiness issue with an appliance, coordination with the appliance manufacturer occurs to ensure that the possible safety risks to all products using the appliance are evaluated and addressed.
TO THE FEDERAL AVIATION ADMINISTRATION: Require airplane manufacturers and modifiers to provide positive separation between electrical wiring and oxygen system tubing according to, at a minimum, the guidance in Advisory Circular (AC) 43.13-1A, Acceptable Methods, Techniques, and Practices Aircraft Inspection and Repair, and AC 65-15, Airframe and Powerplant Mechanics Airframe Handbook.
TO THE FEDERAL AVIATION ADMINISTRATION: Require airplane manufacturers and operators to ensure that oxygen system tubing in proximity to electrical wiring is made of, sleeved with, or coated with nonconductive material or that the tubing is otherwise physically isolated from potential electrical sources.
TO THE FEDERAL AVIATION ADMINISTRATION: Develop minimum electrical grounding requirements for oxygen system components and include these requirements as part of the certification process for new airplanes and approved supplemental type certificate modifications to existing airplanes.
TO THE FEDERAL AVIATION ADMINISTRATION: Once electrical grounding requirements for oxygen system components are developed, as requested in Safety Recommendation A-09-48, require airplane operators and modifiers to inspect their airplanes for compliance with these criteria and modify those airplanes not in compliance accordingly.
TO THE FEDERAL AVIATION ADMINISTRATION: Develop inspection criteria or service life limits for flexible oxygen hoses to ensure that they meet current certification and design standards.
TO THE FEDERAL AVIATION ADMINISTRATION: Once inspection criteria or service life limits for flexible oxygen hoses have been developed, as requested in Safety Recommendation A-09-50, require airplane operators to replace those hoses that do not meet the inspection criteria or that exceed the service life limits.
TO THE FEDERAL AVIATION ADMINISTRATION: Require transport-category airplane operators to (1) perform a one-time inspection of all passenger service unit reading lights installed on their airplanes to ensure that they include rubber boots or use other means to isolate the electrical parts of the assembly and (2) include, in maintenance manuals or other maintenance documentation, information about the importance of this electrical protection.
TO THE FEDERAL AVIATION ADMINISTRATION: Require operators of transport-category cargo airplanes to install smoke detectors in the supernumerary or similar compartment of their airplanes.
TO ABX AIR: Modify your continuing analysis and surveillance program so that all identified chronic discrepancies, such as those affecting the oxygen system on the accident airplane, are effectively resolved.
Sequence of events
1 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)- before engine startpre-flightp.2Fire broke out during pre-start preparations; neither engine was running so the FDR start logic was not met and nothing of the event was recorded
NTSB analysis
from the final reportThe Safety Board’s full report is available at http://www.ntsb.gov/publictn/A_Acc1.htm. The Aircraft Accident Report number is NTSB/AAR-09/04/SUM. On June 28, 2008, about 2215 Pacific daylight time, an ABX Air Boeing 767-200, N799AX, operating as flight 1611 from San Francisco International Airport, San Francisco, California, experienced a ground fire before engine startup. The captain and the first officer evacuated the airplane through the cockpit windows and were not injured, and the airplane was substantially damaged. The cargo flight was operating under the provisions of 14 Code of Federal Regulations Part 121. At the time of the fire, the airplane was parked near a loading facility, all of the cargo to be transported on the flight had been loaded, and the doors had been shut.