CFM International CFM56-5 / -7 Series Engines
(Installed on A319, A320, A340, and Boeing 737 Aircraft)

Permanent Magnet Alternator (PMA) Failure

Transport Canada Civil Aviation (TCCA) is issuing this service difficulty alert to bring to the attention of the operators of these aircraft types, that an un-commanded in-flight shutdown (IFSD) may be prevented by the incorporation of the applicable software update in their engine full authority digital engine control (*FADEC) units.

*Note: The FADEC comprises many components, two of which are the electronic control unit (ECU) and the permanent magnet alternator (PMA).

History

In 2002, an Airbus A340-300 aircraft, equipped with CFM International CFM56-5C series engines, had an un-commanded IFSD on the #1 engine. The investigation revealed the root cause was a permanent magnet alternator (PMA) ball bearing failure. As a result of the rotor to stator contact due to the bearing failure, the PMA was unable to generate reliable electrical power for the ECU.

The ECU continuously monitors the PMA, and if the PMA fails to generate the required electrical power, the ECU will switch to other aircraft electrical power sources. In this incident, the ECU, being subjected to the intermittent nature of the PMA failure, remained in an endless loop switching between aircraft and engine power. With no reliable or consistent source of electrical power, the engine eventually shut itself down.

Reference: Transportation Safety Board (TSB) Report No. A02P0261.

FADEC software version 5.C.3.J, as introduced by CFM56-5C Service Bulletin (SB) 73-0126, November 2003 corrects this situation.

In the event of a power loss from the alternator:

• If the ECU sees a reapplication of power after not having power, it remains latched to aircraft power for the remainder of the flight; and
• A "NO DISPATCH" fault is then generated.

This failure mode logic was not part of the original certification software.

The same problem can also occur on the CFM56-5/-7 series engines.

Failure logic is addressed for these models in the following software versions:

Transport Canada recommends operators with the above series engines installed on their aircraft to incorporate the appropriate Service Bulletin

ps. Transportation Safety Board (TSB) Report No. A02P0261

The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of advancing transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.

Aviation Investigation Report
Engine Power Loss in Flight
Cathay Pacific Airways
Airbus A340-300 B-HXN
Timmins, Ontario 40 nm W
20 October 2002

Report Number A02P0261

Synopsis

The Cathay Pacific Airways Airbus A340-300 (CPA829), B-HXN, departed Toronto/Lester B. Pearson International Airport, Ontario, at 2352 eastern standard time on a scheduled flight to Hong Kong, with a planned refuelling stop in Anchorage, Alaska. There were 249 passengers and 13 crew members on board. One hour and nine minutes into the flight, while cruising at flight level 350, the pilots felt an airframe vibration and observed the number 1 engine shut down spontaneously. All cockpit indications leading up to the engine power loss were apparently normal. The pilots secured the number 1 engine in accordance with the quick reference handbook, continued flight on three engines, and diverted to Vancouver International Airport, British Columbia. CPA829 landed at Vancouver at 0105 Pacific standard time without further incident.

不知有没有人遇到过这种情况,大约四年前我曾经碰到(CFM56-7B),做了很多工作.走了不少冤枉路.现在知道怎么一回事了.

二发一发(2006-03-04 21:07:26)
一只小公鸡(2006-09-03 17:03:02)
本贴已获得点数：★