What happened
Following a standard taxi and takeoff, the crew of a Gulfstream G-V discovered that the landing gear failed to retract after liftoff. After the flight crew attempted to manually raise the gear without success, the decision was made to return to the departure airport. During the landing flare, as the throttles were moved to the idle position, the ground spoilers deployed unexpectedly. This caused the aircraft to descend at a high rate, resulting in a heavy impact with the runway and the subsequent collapse of the right main landing gear. There were no fatalities reported in the incident.
Findings
Investigation into the mechanical failure revealed that a mechanic had placed wooden sticks into the weight-on-wheels (WOW) switches. This was done while the aircraft was on jacks during maintenance to force the switches into ground mode, allowing the technician to access the maintenance data acquisition unit to troubleshoot an overspeed alert issue. The sticks were inadvertently left in place when the aircraft was returned to service, and no documentation regarding the disabled switches was recorded in the maintenance logs.
Because the switches were stuck in ground mode, the aircraft's systems incorrectly indicated the plane was on the ground. This caused the ground spoilers to arm and deploy when the throttles reached idle. Furthermore, the investigation found that the crew did not follow the procedures outlined in the Quick Reference Handbook (QRH) regarding amber WOW FAULT or red GND SPOILER messages. Additionally, the preflight inspection, which included a visual check of the WOW switches, did not identify the obstruction.