Final Report: Microphone Assembly Blocked Control Movement

 - October 31, 2006, 5:03 AM

Challenger 600, Tupelo, Miss., March 9, 2005–Inadequate design of the STCed microphone jack assembly, resulting in restricted aft movement of the control column, was blamed for the accident of Romeo Mike Aviation’s Challenger.

Taking off from Tupelo Regional Airport, the airplane reached V1 (128 knots) and Vr (134 knots) and the 6,157-hour ATP pilot attempted to rotate but the control column would not move aft from the neutral position. Trying to move it aft “felt as if it were locked against a stop.” The airplane was about 4,000 feet down the runway at between 140 and 145 knots. The PIC decided to abort, extended the spoilers, applied maximum braking and maximum reverse thrust and maintained centerline down the runway. The airplane went off the end of the runway and the nosewheel collapsed. No one was injured.

A dual Baker M1045 cockpit audio system had been installed on the airplane under STC SA 4900SW in 1984. When the control column was pulled aft, the handheld microphone audio jack assembly attached to the copilot’s control column bent downward and the audio jack assembly came in contact with the column cover, preventing aft movement.

A new airworthiness directive requires the modification of the microphone jack assembly and repetitive visual checks of the assemblies on both control columns to detect damage that could interfere with the movement of the control column.