Japanese safety investigators concluded that work done by Bombardier on one of its Q400 turboprops before delivery to All Nippon Airways subsidiary Air Central caused a 13 March 2007 incident in which the aircraft's nose landing gear failed to deploy on landing at Japan's Kochi airport.
The latest report by Japan's aircraft and railway accidents investigation commission ARAIC on the damage to the aircraft, registered JA849A, confirms an earlier finding that the failed deployment occurred because a 30mm (1.2in)-long strip of metal bushing moved and prevented the front landing gear doors from opening.
However, while ARAIC originally found the bushing moved because a bolt dislodged, it has now concluded there never was any bolt because the manufacturer failed to install it following repair work carried out before delivery to the airline in July 2005.
ARAIC found that in Bombardier's record there "are no documents indicating the work procedures or records of specific inspections to the work nor were there any descriptions of the bolt tightening torque value for connecting the toggle links". The landing-gear supplier Goodrich has drawings specifying the bolt tightening torque, but Bombardier's assembly manual fails to have this detail, it says.
ARAIC says it will ask Transport Canada to "encourage Bombardier to improve further their quality control system, especially concerning repairs".
Bombardier in a statement expresses its regret about the accident and adds that it has "already implemented many of the recommendations proposed in the report".
Japan Airlines and ANA grounded their entire fleets of Bombardier Dash 8-100s, Q300s and Q400s following the incident because the Japanese authorities issued a directive requiring that all Dash 8s be temporarily grounded for a visual inspection of the front landing gear.