Mx manual scrutinized in Colgan 1900D crash

 - March 19, 2008, 6:46 AM

An FAA review of maintenance procedures following the August 26 crash of a Colgan Air Beech 1900D near Hyannis, Mass., has found that Raytheon service manuals incorrectly depict the installation of a key part of the airplane’s elevator trim system. The agency has issued an AD on all Beech 1900s, 1900Cs and 1900Ds, effective October 15, that requires operators to revise their manuals with a corrected illustration of the elevator trim drum assembly. Although the written instructions in the manual are correct, the illustration depicts the cable drum at 180 degrees from the proper installed position and erroneously shows the open, keyed side of the drum rather than the flat side.

The day before the Colgan Air ferry flight that ended with the death of both pilots, maintenance personnel replaced two trim-tab actuators and the airplane’s forward elevator trim cable. Two days before the January 8 crash of another Beech 1900D in Charlotte, N.C., where all 21 occupants aboard a scheduled Air Midwest flight died, a mechanic allegedly misrigged that airplane’s elevator control cable.

Although the FAA said the investigation into the most recent crash uncovered the manual irregularity, it did not draw a direct connection in either case, and stressed that the written instructions are correct.

However, during an NTSB hearing into the Charlotte disaster in May, testimony centered on the clarity of the instructions in the manual used by the mechanic who performed the rigging on the ill-fated turboprop. In February Air Midwest wrote to the NTSB that the manual “lacked explicit instructions, which, if included, could have avoided the elevator misrigging.” Nevertheless, under FAA rules the airlines themselves–not Raytheon–carry the final responsibility for the content of their manuals.

NTSB investigations into both accidents continue, and could last well into next year.