ERA13LA175

The pilot reported that when he attempted to extend the landing gear, he heard a "snap," and the landing gear did not extend. He then cycled the landing gear and attempted the emergency (manual) landing gear extension procedure with no success. The pilot subsequently performed a gear-up landing to a grassy area at an airport. Examination of the airplane revealed that the emergency gear extension cable terminated with a spline drive at the landing gear actuator. The emergency cable was separated from the spline drive, which was seized. The emergency gear extension cable was also misrigged, which allowed it to contact the landing gear actuator arm and engage the cable during normal gear operations. Subsequently, with a seized spline engaged to the electric landing gear motor via the actuator, during normal gear operations, the electric landing gear motor would not be able to overcome the seized spline to actuate the landing gear. The airplane had been operated about 60 hours since its most recent annual inspection, which was completed about 10 months before the accident. Review of the airplane's most recent airframe logbook (dating back 7 years) revealed that the landing gear actuator was removed and replaced about 4 years before the accident. During reinstallation of the actuator, an emergency (manual) gear extension was successfully completed. There were no other entries pertaining to emergency (manual) gear extension in the airframe logbook; however, the entry for the most recent 100 hour inspection noted three landing gear retraction cycles. The mechanic that recorded that entry stated it was a standard entry and typically more than three cycles are completed with the first one being the emergency (manual) extension. While it was likely that a mechanic checked the rigging of the emergency gear extension cable following the actuator replacement, the investigation was unable to determine if the rigging of the emergency gear extension cable was affected by any subsequent maintenance. Additionally, the cable routing and rigging wouldn't typically be inspected if the landing gear manual extension was successfully accomplished during the 100-hour or annual inspections.

On March 16, 2013, about 1130 eastern daylight time, a Mooney M20F, N9387V, operated by a private individual, was substantially damaged during a gear-up landing at Leesburg International Airport (LEE), Leesburg, Florida. The commercial pilot was not injured. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local flight that departed LEE about 1030. The pilot reported that while practicing slow-flight, he attempted to extend the flaps and landing gear. The flaps extended, but he heard a "snap" and the landing gear did not extend. Additionally, there was no cockpit indication of the landing gear being retracted or extended. Utilizing the pilot operating handbook, he cycled the landing gear with no success. He then attempted the emergency (manual) landing gear extension procedure, also with no success. The pilot subsequently performed a low pass and LEE control tower personnel confirmed that the landing gear was not extended. The pilot then performed a gear-up landing on a grassy area at LEE. The airplane came to rest upright; however, the empennage sustained substantial damage. The airplane was examined by a mechanic, under the supervision of a Federal Aviation Administration inspector. The mechanic stated that the emergency (manual) gear extension cable terminated with a spline drive at the landing gear actuator. He observed that the emergency gear extension cable spline drive was seized and the cable portion behind it rotated freely in its sheath. The mechanic added that at some point in the airplane's history, the emergency gear cable separated from its terminating spline drive. This would not normally affect the landing gear system unless the emergency landing gear extension cable was engaged from the cockpit via a knob. However, the mechanic also noted that the emergency gear extension cable was previously mis-rigged, which allowed it to contact the actuator arm and engage the cable during normal gear operations. Subsequently, with a seized spline engaged to the electric landing gear motor via the actuator, during normal gear operations, the electric landing gear motor would not be able to overcome the seized spline to actuate the landing gear. Review of the airplane's most recent airframe logbook revealed entries dating back to May 2006. Further review of the airframe logbook revealed that the landing gear actuator (part number 4196-00-1C) was removed and replaced on February 16, 2009. Following its replacement, maintenance personnel cycled the landing gear five times, checked the emergency (manual) landing gear disengage system, and manually extended the landing gear. There were no other entries pertaining to the emergency gear extension system in the airframe logbook; however, the logbook entry for the most recent 100-hour inspection noted "performed three landing gear retraction cycles." The airplane's mostrecent 100 hour inspection was completed on May 24, 2012. Review of a Mooney Maintenance Manual, 100 Hour-Annual Inspection Guide, revealed "8. Check emergency landing gear extension system; extend gear using emergency gear extension system." The mechanic that had completed the most recent 100 hour inspection reported that he typically does more than the standard airframe logbook entry of three landing gear retraction cycles, with the first one being done manually (emergency), which was what he performed on the accident airplane. The mechanic added that the standard logbook entry does not differentiate between normal or emergency gear retraction cycles. Additionally, he was very familiar with that airplane as he had owned it for 14 years prior to its current owner and did not experience any problems with the landing gear system during the most recent inspection or prior. At the time of the most recent 100 hour inspection, the airplane had accumulated 3,497.9 total hours of operation. The airplane had accumulated an additional 59 hours of operation, from the time of the last annual inspection, until the accident.