NTSB Identification: WPR09LA417
14 CFR Part 91: General Aviation
Accident occurred Wednesday, August 26, 2009 in Wendover, UT
Probable Cause Approval Date: 07/22/2010
Aircraft: PIPER PA28R, registration: N4837T
Injuries: 3 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot said that after takeoff he was unable to retract the landing gear, and at about the same time perceived a loss of engine power output. The pilot then set the mixture control to full rich and leveled the airplane. When attempts to retract the landing gear were unsuccessful, the pilot elected to make an emergency landing on an interstate highway. During the landing the airplane’s left wing impacted the left side of a tractor-trailer truck, which resulted in substantial damage to the airplane. The engine was test run 3 separate times during a post accident examination and no anomalies were noted that would have precluded normal operation. The airplane was equipped with a landing gear back-up actuator override mechanism, which prevents landing gear retraction at airspeeds below approximately 85 miles per hour (mph); this airspeed increases with power reduction and/or altitude increase. Density altitude at the time of the accident was calculated to be 6,946 feet, which according to Piper Aircraft, would have required an additional 6 miles per hour to be added to the 85 mph to affect a normal gear retraction. The system incorporates a manual override emergency gear lever that in the raised position allows the landing gear position to be controlled by the landing gear selector switch regardless of airspeed and power combinations. A post accident examination of the override system revealed no anomalies that would have precluded normal operation. When asked if he had used the system prior to the emergency landing, the pilot said he had not. The pilot’s failure to attain and maintain an airspeed sufficient to affect a normal landing gear retraction, as well as his failure to utilize the airplane’s emergency landing gear override system, collectively contributed to his decision to make an emergency landing. The pilot’s perceived loss of engine power was most probably due to the degraded engine performance as a direct result of positioning the mixture control from an optimal lean position to the full rich position in a high density altitude environment. The pilot could have mitigated the event had he elected to initially use the manual override system, which would have resulted in a normal gear retraction regardless of airspeed and altitude.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The failure of the pilot to attain and maintain an airspeed sufficient for normal landing gear retraction during initial climb. Contributing to the accident was the pilot's failure to use the airplane's manual override landing gear system, misidentifying that a total loss of engine power was imminent, positioning the mixture control to the full rich position, and the density altitude condition. Full narrative available
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