U.S. GIV Owners Have 36 Months To Retrofit Gust Locks

U.S. owners and operators of Gulfstream GIVs, GIV-SPs, G300s, and G400s have 36 months from today to comply with FAA AD 2017-13-11, which requires modification of the gust lock system and a revision of the maintenance or inspection program to incorporate functional tests. This action stems from NTSB safety recommendation A-15-31 outlined in its final report of the GIV that crashed on takeoff from Massachusett’s Bedford-Hanscom Field in May 2014. All four passengers and three crewmembers were killed.

During the engine start process, the flight crew neglected to disengage the airplane’s gust lock system before initiating takeoff, as well as neglected to perform a flight control check that would have alerted them of the locked flight controls. During the takeoff roll, the flight crew noticed that the controls were locked. The twinjet overran the runway, struck lights, came to rest in a gully, and caught fire.

The GIV has a mechanical interlock between the gust lock handle and the throttle levers that restricts the movement of the throttle levers when the gust lock handle is in the ON position. This mechanism was intended to limit throttle lever movement no more than 6 degrees during operation with the gust lock on. However, post-accident testing on nine in-service GIVs found that, with the gust lock handle in the ON position, the forward throttle lever movement was three to four times greater than that limit.