What happened
On June 2, 2011, a Piper PA-46-310P, registration N712MK, was on approach to Lake Havasu City Airport in Arizona when the pilot experienced a failure in the landing gear extension system. The flight had originated from Portland, Oregon, earlier that morning. After canceling the instrument flight rules (IFR) clearance and entering the traffic pattern, the pilot attempted to lower the landing gear but received no response.
In an attempt to resolve the issue, the pilot reset the landing gear circuit breaker and re-attempted the extension, but the gear remained retracted. The pilot then followed the emergency checklist and attempted to use the emergency gear release, which also failed to work. For approximately 90 minutes, the pilot continued to follow emergency procedures while managing declining fuel levels. Upon reaching minimum fuel, the pilot prepared for a gear-up landing by securing the cabin, feathering the propeller, and shutting down the engine and all electrical and fuel controls. The aircraft touched down at midfield and slid approximately 1,200 feet down the runway, resulting in no injuries but substantial damage to the aircraft, including a ground-down lower fuselage bulkhead.
The investigation
An FAA airworthiness inspector examined the aircraft while it was on jacks with electrical power applied. The investigation determined that both the normal and emergency extension systems were non-functional. While the gear was eventually lowered by bleeding pressure from a fitting on the nose gear sequence valve, the emergency release valve (P/N 85124-02) was found to be malfunctioning. The control arm on the valve moved only 1/4-inch, failing to reach the required 2-inch movement. This restricted movement prevented the valve from porting hydraulic fluid from the gear-down line to the gear-up line, which is necessary to allow fluid to return to the reservoir and permit gravity to extend the gear.
Findings
- The normal gear extension system failed due to a faulty low pressure switch.
- The emergency gear release valve was misrigged, preventing the necessary hydraulic fluid movement for gravity-assisted extension.