NTSB Factual Report

On November 24, 2012, about 0800 mountain standard time, a Piper PA-30, N8747Y, sustained substantial damage following a landing gear collapse during landing roll at the Deer Valley Airport (DVT), Phoenix, Arizona. The airplane was registered to and operated by Twin Comanche LLC. The certified airline transport pilot and two passengers were not injured. The local flight was being operated in accordance with 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed and a flight plan was not filed. The flight departed DVT about 30 minutes prior to the accident.

In a written statement provided to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that he had not flown the airplane for almost 3 months prior to the accident. The pilot further reported that he started the right engine on external power, unplugged the external power, and then started the left engine using the airplane's electrical system, with the ammeter showing a normal charge rate at one-quarter scale. The pilot stated that immediately after takeoff the airplane experienced a total electrical failure, at which time he attempted to reset the alternators, voltage regulators, and battery switches; however, he was unable to restore electrical power. The pilot reported that he then called Flight Service to have them relay his situation to the DVT air traffic control tower, in order for them to give him a light signal for clearance to land. Prior to receiving the light signal, the pilot stated that he flew a wide circle to the north and west while performing the emergency landing gear extension procedure. He stated that it did not appear that the [landing] gear had retracted at all, as the emergency extension lever was already vertical when inserted into the left socket. He added that he then pulled the release lever and pushed the lever forward per the [emergency] procedures, but could not verify electrically if the gear was locked. The pilot stated that the viewing mirror on the left engine nacelle indicated that the nose gear "looked good."

The pilot reported that he touched down smoothly on Runway 7L with the main landing gear, but when the nose gear touched down, all 3 landing gear retracted. The airplane subsequently slid off of the right edge of the runway and came to rest in a rock covered area, which resulted in substantial damage to the undercarriage of the airplane.

In a conversation with a Federal Aviation Administration (FAA) airworthiness inspector who conducted a postaccident examination of the airplane, the inspector reported that an examination of the landing gear motor where it attaches to the airframe revealed what looked like a fracture. He stated that the fracture looked clean, it appeared to have failed in overload, and that it was most likely a result of the accident. The inspector further stated that he thought that the most probable explanation of what caused the loss of electrical power had to do with the Master Switch failure or intermittent operation of the switch. A follow-up examination of the Master Switch by the NTSB IIC revealed that it functioned properly with no anomalies noted.

An examination of the aircraft maintenance records revealed that the most recent annual inspection was performed on July 16, 2012, at which time the airplane's battery would have been checked in accordance with the Piper Aircraft PA-30 Service Manual. No anomalies were noted during the inspection.

According to the Piper Aircraft Corporation Report 1515, FAA Approved Flight Manual for Piper Twin Comanche, Model PA-30, applicable to serial number 30-1717 and 30-1745 and up, date of approval February 5, 1963, the instructions for the Emergency Extension of the Landing Gear state:

• Reduce power/airspeed not to exceed 100 miles per hour.

• Place landing gear selector switch in the "GEAR DOWN LOCKED" position.

• Disengage motor. Raise motor release arm and push forward thru full travel.

• Remove gear extension handle from stowage. If left socket is not in clear position, place handle in right socket. Engage slot and twist clockwise to secure handle. Extend handle and rotate forward until left socket is in clear position. Remove handle and place in left socket and secure. Extend handle. Rotate handle FULL forward to extend landing gear and engage emergency safety lock.

• Handle locked in full forward position indicated landing gear is down and emergency safety lock engaged. Gear "DOWN LOCKED" indicator light should be "ON".

Note: Reducing power and rocking gear extension handle will aid in manually extending the landing gear. DO NOT RETRACT WITH HANDLE IN SOCKET. DO NOT RE-ENGAGE MOTOR IN FLIGHT.

NTSB Probable Cause

The pilot's failure to properly inhibit the landing gear transmission motor consistent with the emergency landing gear extension procedure, which precluded the full extension of the landing gear. Contributing to the accident was the airplane's electrical system anomaly, which rendered the gear position indicator inoperative.