A flight data recorder (FDR) problem is the subject of a Dec. 2, 2003, Federal Aviation Administration (FAA) special airworthiness information bulletin (SAIB No. CE-04- 24). The bulletin is an outgrowth of the fatal February 2000 crash of an Emery Worldwide Airlines DC-8 freighter (see ASW, Aug. 11, 2003). To highlight the crucial issue, the L-3 Communications (formerly Loral Fairchild) Model F-800 digital FDR (DFDR) loses data when electrical power is lost. More specifically, when this happens the FDR switches to the first track of the recording tape, and this track-switching malfunction results in lost data on the 25-hour tape loop. The F-800 has a troubled performance history and has been a bane to investigators in a number of accidents and incidents.

The SAIB intones:

"Proper operation of an aircraft's FDR system contributes directly to increased aircraft safety and is necessary ... to keep 25 hours of oldest recorded data ... Improper management and maintenance of the aircraft's FDR can contribute to loss of recorded data that could be vital in determining the cause of aircraft accidents and aircraft systems failures."

The SAIB urged operators to comply with two field service bulletins issued by Loral Fairchild to remedy the problem.

Unlike airworthiness directives (ADs), SAIBs are not mandatory. Indeed, the caveat is printed right at the top: "This is information only. Recommendations aren't mandatory."

Hence, non-mandatory compliance with non-mandatory service bulletins is being urged. By distinct contrast, other agencies consider it necessary to require corrective action. One of those agencies is the National Transportation Safety Board (NTSB). After the Emery crash, the board sought required SB compliance. The board classified the FAA response to that particular recommendation as "Open - Await Response." Since the board's recommendation uses the word "require" in its call for SB compliance, it will be interesting to see the board's reaction when it does receive a direct response from the FAA. Given the specific wording of the NTSB's recommendation, and the fact that improved maintenance of recorders is on its "Most Wanted" list of safety improvements, it would appear that an SAIB issued for informational purposes only is not likely to satisfy the NTSB - or should not.

A policy question arises: at what point does a problem, especially one related to devices recording the [mal]functioning of flight critical systems, rise to the level of AD action?

The FAA responded: "FDR data is important, but not every issue identified rises to the level of issuing an AD. As you know, there must be an 'unsafe condition' identified to put out an AD. That's the prime criterion."

Yes, but - a faulty or inoperative FDR can lead to the loss of vital information that could perpetuate an unsafe condition. This is precisely the point made by the FAA in justifying its Jan. 9 required action regarding FDRs on Bombardier CL-600 regional jets. The work is required, the final rule intones: "The lack of data from FDR and CVR [cockpit voice recorder] equipment could hamper discovery ... and prevent the FAA from developing and mandating actions to prevent additional accidents or incidents caused by that same unsafe condition."

A Bane to Investigators

From the UK Air Accidents Investigation Branch (AAIB) report of a collapsed nosewheel accident in October 2000 at Bournemouth Airport involving an ATR-72 (extracts):

"On replay [of the Model F-800 FDR] ... the quality of data was very poor. Of the six tracks, two contained little or no decodable data. The others contained a number of areas where there were extensive periods of indecipherable data and many isolated instances of poor data.

"The figure for the final touchdown could not be calculated because of loss of recorded data.

"Apart from this accident, the F-800 DFDR has a history of poor performance for accident investigation purposes.

"In 1994 an ... A320 took off with the slats locked out. The F-800 DFDR provided no useful information ... In 1999 a Greek registered Dassault Falcon 900 encountered a severe in-flight upset in which 5 passengers were killed. The Greek authorities asked for AAIB's assistance to recover some areas of bad data from the F-800 recorder ... After about a week of work, only about 50% of the information could be recovered.

"It is known that the Bureau Enquetes Accidents (BEA) in France [has] experienced numerous difficulties with the F-800 recorder and [has] considered a recommendation to have it banned." (ASW note: In a high profile accident involving the 1992 crash of an Air Inter A320 near Mt. Saint-Odile in France, , the BEA report noted with dismay that the F-800 DFDR failed to provide any data.)

"If confirmed to be not satisfactory for accident investigation purposes, they should remove it from the approved list of recorders that may be fitted to aircraft."

From Federal Aviation Administration 1997 revisions to digital FDR rules, in particular:

"Airborne Express comments that lateral acceleration cannot be recorded at the specified monitoring interval using the Loral F-800 flight data recorder." (For more, see www1.faa.gov/avr/arm/a121-266.doc)

From the U.S. National Transportation Safety Board (NTSB) investigation into the fatal Feb. 16, 2000, crash of an Emery Worldwide Airlines DC-8 freighter:

"The Safety Board's examination of the data from the accident airplane's FDR (a Loral Fairchild F-800 model) revealed an anomaly with the recorded elevator position data, which complicated this investigation and delayed ... recognition of the significance of the elevator movement during the accident sequence.

"The Safety Board has previously observed track-switching anomalies with other F-800 model FDRs." (For more, see www.ntsb.gov/Recs/letters/2003/A03_22_36.pdf)

Not Requesting - Requiring

U.S. National Transportation Safety Board, Aug. 18, 2003, letter to the Federal Aviation Administration (extracts):

"Require all operators of airplanes equipped with Loral Fairchild Model F-800 flight data recorders to comply with Loral Fairchild Field Service Bulletins." (Emphasis added) Recommendation No. A-03-34. Current status: Open - Await [FAA] Response (For more, see www.ntsb.gov/Recs/letters/2003/A03_22_36.pdf).

Civil Aviation Safety Authority of Australia:

AD/A320/77, Loral DFDR F-800, for Airbus A319, A320 and A321 airplanes:

"Airbus Industrie advises that under certain flight conditions the DFDR may not record all necessary data correctly. Action specified by this directive [is] designed to rectify this discrepancy." (See www.casa.gov.au/avreg/aircraft/ad/adfiles/over/a320/A320- 077.pdf )

AD/REC/4, Fairchild Model F-800 DFDRs (all):

"Requirement: Action in accordance with Loral Data Systems, Fairchild Aviation Recorders Bulletin DFR 027. Note: This modification has been classified as mandatory by the Bureau of Air Safety Investigation, Department of Transport and Communications (emphasis in original).

"Compliance with this Directive will ensure that faults are detected and information critical to the investigation of an accident or incident is not lost." (See www.casa.gov.au/avreg/aircraft/ad/adfiles/equip/rec/REC-004.pdf)