Gulfstream GIV-SP HI1050, Photograph courtesy of The Latin American Aviation Historical SocietyGulfstream has released maintenance and operations letters (MOLs) for spoilers on Gulfstream GII, GIIB, GIII, GIV and G450 aircraft after a Gulfstream GIV-SP impacted the ground during a landing attempt at the Las Americas International Airport in the Dominican Republic last December. The crash killed all nine on board.
"This information re-emphasizes the critical importance of performing a full spoiler functionality check on the ground, as detailed in the respective Aircraft Flight Manual or Operations Manual," noted the Dominican Republic Aviation Accident Investigation Commission (CIAA), which is investigating the fatal crash.
The Gulfstream IV-SP, registered HI-1050, was operating under the Dominican Republic Part 135 regulations as a charter flight to Orlando, Florida. A preliminary report issued in January by the CIAA notes that both the right ground and flight spoiler actuators were removed and replaced before the passengers boarded the flight.
According to the report, the spoilers on the right wing did not retract during a control check by the pilot. The aircraft appeared to taxi with the spoilers on the right wing extended while those on the left were retracted.
The flight crew declared an emergency shortly after takeoff, diverting to Las Americas International Airport and hitting trees on approach before landing to the right of the runway.
The MOLs encourage operators to utilize a flight control synoptic page during ground spoiler functional check procedures. If the aircraft is not equipped with one, crews should "confirm visually the spoiler panel position utilizing the side windowpane mirrors or utilize a ground or cabin window observer."
The CIAA and Gulfstream also stressed the importance of adding visually identifiable markings to hydraulic lines to help reinstall the lines to correct actuator ports.
"Failure to reconnect the hydraulic lines to the proper actuator ports may result in improper operation of the ground flaps, including asymmetrical deployment and operation during flight, which could lead to loss of control," the MOLs added.
The investigation is still ongoing, but a final report is expected to be published by the CIAA in the coming months.