NTSB Scrutinizes Landing Gear in Learjet Accident in Arizona

The February 10 accident occurred around 2:39 p.m. MST during VFR conditions when a Learjet 35A arriving from Austin, Texas, veered off the runway and struck a parked Gulfstream G200.

Video of the aircraft on approach showed that the left main landing gear of the Gates Learjet 35A was trailing and not in the down-and-locked position, according to a preliminary accident report released by the National Transportation Safety Board (NTSB).

The Learjet pilot was killed, and the first officer and one passenger were seriously injured, another received minor injuries. A person aboard the parked Gulfstream sustained serious injuries.

According to the NTSB report, investigators obtained security camera footage and numerous cell phone videos, some taken from a golf course near the final approach path. In one 11-second video showing the aircraft on final approach, the left landing gear was trailing aft from its normal position.

When the Learjet touched down, its left wing hit the pavement, causing the aircraft to slide out of control, off the runway and cross a taxiway and the ramp before colliding with the parked Gulfstream G200.

"Additionally, there is a circular bright spot seen above the landing gear strut, consistent with the landing gear light illuminating the bottom of the wing flap and the landing gear strut positioned facing aft," the NTSB report (below) said.

According to NTSB, the flight crew did not make any radio calls indicating it was aware of an issue with the landing gear. 

The landing gear control panel is located on the right side of the center instrument panel. When the landing gear is down and locked, three green lights illuminate. If the gear is not down and locked, three red lights indicate an unsafe condition. A down-and-locked switch on each actuator housing illuminates the corresponding lights. If the actuator is not locked, the light remains off. Each main gear’s red "unsafe" light is triggered by a microswitch on the inboard gear door—the light shows when the door is open and turns off when the door closes.

The Learjet's main landing gear is electrically controlled and hydraulically actuated, NTSB said.

"Each main gear assembly consists of a conventional oleo shock strut, dual forged wheels with multiple-disc brakes, a main gear actuator, and inboard/outboard doors hinged at the wing structure,” the report said. “The assembly attaches to the airplane structure through trunnion pins, with striker plates on the trunnions to actuate microswitches. The aft trunnion pins are positioned with the shoulder abutting the aft trunnion fitting and the body is aligned forward through a bushing where there is a grease hole on the pin and into the aft trunnion casting. There are shims that are placed on the pin and positioned on both sides of the aft trunnion fitting to ensure adequate movement. The pin is secured to the trunnion with a retention bolt that goes through the striker bracket, trunnion, and the pin’s retention bolt holes, which is then affixed with a castellated nut and cotter pin."

According to the report, the left main landing gear came to rest on Taxiway Bravo 10 with the forward trunnion pin remaining secured in the forward trunnion casting. 

"The aft trunnion pin was not present within the trunnion casting, though the retaining bolt with striker bracket was secured with the castle nut and cotter pin,” NTSB said. “The actuator remained connected to the strut, but the inboard attachment point was no longer fastened to the airframe. The right main landing gear remained attached to the airframe and was in the down and locked position with the outboard gear door separated and located within the debris field and the inboard door in the locked position."

The left outboard gear door was not located, and the inboard landing gear door was not in the uplock position. Removal of the access panel adjacent to the aft trunnion revealed the aft trunnion pin’s shoulder and the aft shims with what was described as an excessive amount of grease piled below the pin.

The right main landing gear remained attached to the airframe and was in the down-and-locked position with the outboard gear door separated and located within the debris field and the inboard door in the locked position.

The flight crew of the accident airplane was involved in a landing mishap in June 2024 in McAlester, Oklahoma, according to NTSB. The aircraft landed hard and bounced several times resulting in the failure of the main landing gear tires. The owner of the aircraft hired a mechanic who had it ferried to his shop to do required inspections after the event.

A mechanic who performed landing gear servicing on the aircraft in December told investigators that there was nothing unusual about the left landing gear, however, it took an excessive amount of grease.