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Last updated: 28 October 2021
Date:Sunday 24 November 1985
Type:Silhouette image of generic GLF2 model; specific model in this crash may look slightly different
Grumman American G-1159 Gulfstream II
Operator:Gulfstream Aerospace
Registration: N104AR
MSN: 140
First flight: 1974
Crew:Fatalities: 0 / Occupants: 3
Passengers:Fatalities: 0 / Occupants: 3
Total:Fatalities: 0 / Occupants: 6
Aircraft damage: Substantial
Aircraft fate: Repaired
Location:Edmonton International Airport, AB (YEG) (   Canada)
Phase: Landing (LDG)
Departure airport:?
Destination airport:Edmonton Municipal Airport, AB (YXD/CYXD), Canada
On final approach to Edmonton Municipal Airport, the indicator light for the right main gear showed unsafe when the landing gear was lowered. The pilot discontinued the approach and was directed to Edmonton International Airport. He circled the airport until 1,000 pounds of fuel remained on board. While circling, the landing gear was cycled four times, after which both main gear lights remained unsafe. The emergency lowering system was activated but was unsuccessful.
Shortly after touchdown, the right main gear collapsed, and the aircraft veered to the right, off the runway.
Investigation at the scene failed to determine the cause of the gear's collapsing, but it was determined that the right main gear side brace (hydraulic actuator) was not in the locked position. Until the main gear side braces are fully extended, the unsafe gear light remains on. It is believed that the left side brace locked in the down position, during the landing roll.
The side braces were removed and examined at the manufacturer's facility. During the test of the right side brace, pressure higher than that normally supplied by the aircraft hydraulic system was required to operate the side brace. The emergency landing gear extension operated normally, but the additional pressure required to lower the landing gear caused the emergency system to be ineffective. A set of new gland seals was installed, and the side brace tested satisfactorily under normal operating pressures. No defects were found in the side brace gland seals that were removed. It could not be determined why above normal pressure was required to operate the side brace.

Probable Cause:

Cause Related:
1. During the landing, the right main gear side brace did not fully extend and lock, and the gear collapsed.
2. For undetermined reasons, above normal hydraulic pressure was required to operate the right main gear side brace.

Landing gear collapse
Runway excursion

» CASB Report 85-W50906


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