Pilots of a Raytheon Hawker 800XP business jet were performing a post-maintenance stall test during a 16 October flight that ended with the jet crashing in Michigan, killing all three people aboard.
The US National Transportation Safety Board (NTSB) says in a preliminary investigation report that a stall test had been required after maintenance technicians performed inspections of the jet’s wings.
The inspections involved removing and replacing the wing’s leading edges and “ice protection panels”. The work was performed by maintenance firm Duncan Aviation at its facility in Battle Creek, Michigan.
Duncan had given the jet’s primary captain a list of “experienced test pilots, for hire, to perform the post-maintenance stall test flight”, says the NTSB. “After being unable to coordinate the stall test flight with a test pilot, the flight crew elected to perform the post-maintenance stall test themselves.”
“The stall flight was part of a test flight conducted at the completion of a scheduled maintenance event performed by Duncan,” that company says.
“Our focus is on supporting the families and friends of the crew, our team members who worked on the aircraft and developed close relationships with the aircraft’s representatives, the aircraft owner and anyone else touched by the tragic event,” says Duncan president Mike Minchow.
The jet took off at 17:08 local time from Battle Creek Executive airport and climbed to 15,000ft, then at 17:27 “began a rapid descent”, during which one of the pilots said over the radio that they were “in a stall, recovering”.
The Hawker slammed into the ground and most of its wreckage was consumed by fire.
The crash killed two pilots and their maintenance representative, but no Duncan employees, Duncan says.
“The NTSB has investigated at least three other accidents/incidents involving the performance of required stall tests after maintenance in business jets,” the report says.
It notes that the jet’s pilot operating manual describes procedures for and warnings about completing stall tests.
“Pilots conducting stall checks should have prior experience in performing stalls in the Hawker and must be prepared for unacceptable stall behaviour at any point leading up to and throughout the manoeuvre,” the manual says.
Story corrected on 14 November to note that the jet took off at 17:08 local time, not 17:28.
