NTSB Advises FAA to Revise Fan Cowl Attachment Procedures

Air Safety Week, Oct 20, 2008

Citing numerous instances over the past several years in which engine fan cowls flew off Airbus A320s and Bombardier CL-600s during flight, the National Transportation Safety Board (NTSB) has sent four new recommendations to the Federal Aviation Administration.

The Safety Board is concerned that the procedures for checking that engine fan cowls are latched properly are inadequate.

The NTSB said "the issue of engine fan cowl separations has been an ongoing problem." The Safety Board reviewed records from Bombardier, Airbus, foreign investigations, and Federal Aviation Administration (FAA) service difficulty reports (SDRs) related to engine fan cowl separations. This review found that, since 1992, there have been 15 events involving Airbus SA model airplanes; another 26 engine fan cowl separations occurred on 17 different airplane models since 1992. In addition, Board queries to Bombardier revealed 33 domestic and foreign cases of engine fan cowl separations (including six cases in 2007 alone), dating back to January 2001.

Despite the release of an FAA airworthiness directive (AD) for Airbus SA airplanes and numerous bulletins for Airbus SA and Bombardier CL-600 airplanes, engine fan cowl separations from Airbus SA and Bombardier CL-600 airplanes have continued to occur.

"The Safety Board believes that the FAA should require all operators of Airbus SA and Bombardier CL-600 airplane models to revise existing AMM procedures and maintenance inspection documents to require a dual inspection signoff to confirm that engine fan cowls are latched after completing any engine maintenance that involves the opening of an engine fan cowl."

The Safety Board also said it was concerned that an engine fan cowl separation could lead to substantial damage to other aircraft and affect the safety of flight. The NTSB said that the risk of other airplane models experiencing engine fan cowl separations is unknown but potentially hazardous.

The NTSB recommends that the FAA:

Require all operators of Airbus single-aisle and Bombardier CL-600 airplane models to revise existing aircraft maintenance manual procedures and maintenance inspection documents to require a dual inspection signoff to confirm that engine fan cowls are latched after completing any engine maintenance that involves the opening of an engine fan cowl. (A-08-79)

Require all operators of Airbus single-aisle and Bombardier CL-600 airplane models to require maintenance personnel to inform flight crews when engine fan cowls have been opened before flight. (A-08-80)

Require all operators of Airbus single-aisle and Bombardier CL-600 airplane models to provide guidance to maintenance personnel and flight crews on how to inspect engine fan cowls to verify that they are latched properly. (A-08- 81)

Determine the extent of the problem of engine fan cowl separations on all airplanes and, should a widespread problem exist for any airplanes, require operators of those airplanes to include a dual inspection signoff in their maintenance procedures to confirm that engine fan cowls are latched after completing any engine maintenance that involves the opening of an engine fan cowl. (A-08-82)

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