An short initial report [from PBL] appeared in Risks, based on information from Flight International, 5-11 June 1996. This stated that the crew of a Martinair B767-300 registration PH-MCH `faced blank flight-instrument displays' near the US coastline on a flight from Amsterdam to Orlando, FL on 28 May 1996. Apparently it had suffered an EFIS failure (EFIS is the industry acronym for the system which displays the flight data on screens in front of the pilots -- a feature of most modern transport aircraft.

The EFIS failure itself was not such a big issue. The plane continued on the electro-mechanical standby instruments and diverted to Boston, where it landed safely -- but very fast, with no flaps, spoilers, autobrake or anti-skid. It burst 8 mainwheel tires and the brakes caught fire (neither event unusual in a fast landing and heavy stop) and the fire was quickly extinguished. Martinair said the crew employed `flaps one', which extends leading-edge spoilers only, and that they had no reverse thrust.

Martinair said the aircraft had a partial DC-power failure, but an unnamed 767 captain apparently said that such an event would not cause an EFIS failure. Boeing said reports of a complete power failure are `not confirmed'.

Flight International, 19-25 June, p9, says that a high-capacity flight data recorder is being fitted to the Martinair 767-300ER which suffered total EFIS failure and partial flight-control loss (FI's words) on 28.5.96 before return to service. Robert Hancock of the NTSB says that they're worried about the crew's lack of information when the problem occurred. They've identified the areas in the DC buses where the power interruptions occurred, but they don't know the initiating event.

Aviation Week and Space Technology issues for Jun 3 and June 10 1996 give the following information, summarised by Robert Dorsett [RDD]: Nearing Boston, the B767-300ER suffered a partial electrical failure, which mainly seemed to involve DC busses. This resulted in the loss of all electronic flight instrumentation. From the reports, EICAS was operational. The incident was preceded by a number of anomalies, including spurious autopilot disconnects, clocks that went blank, and loss of the transponder. They also had spurious zero fuel weight warnings on the EICAS. The failure did not involve communications, and the captain recovered the use of his EADI on approach to Boston. For an unspecified reason, the crew opted for a flaps 1 approach, resulting in a VRef 10 knots higher than would otherwise be the case, and resulting in a longer landing distance. On landing, they lost the air/ground sensing, and the airplane got stuck in the "air" position. So they lost automatic speed brake deployment and thrust reversers. Antiskid performance was also degraded. The crew manually deployed flight spoilers to assist in getting max weight on the wheels. Ground spoilers would not deploy without A/G sensing. The airplane was ferried to Seattle for inspection. It is not clear from the reports whether they had recovered the systems for the flight. The following features are interesting:

• The fact the failure mode occurred at all.
• The Boeing B767 apparently does not have A/G sensing on brakes (cf. the USAir F-100 incident at ORD, in which the crew were unable slow down, because all braking devices were coupled to A/G sensing.
• Because of the loss of A/G sensing, the FADECs on the engines were stuck into a "flight idle" mode, rather than "ground idle," so were generating more thrust than would otherwise be the case. This is the first time I [RDD] have seen this behavior play a part in such an incident
• There was no warning to the aircrew that A/G sensing was also lost, so the consequences of this only became apparent at the last minute. It is not clear from the articles whether they factored this possibility into their landing distance requirements; if not, it would suggest a deficiency in operating procedures.
• It is not clear whether the FMCs were lost.

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Copyright © 1999 Peter B. Ladkin, 1999-02-08
	Last modification on 1999-06-15 by Michael Blume