NTSB Factual Report

**This report was modified on January 9, 2017. Please see the docket for this accident to view the original report.**

On September 13, 2016, about 0840 eastern daylight time (EDT), the right main landing gear on a Piper PA-28R-201, N786GB, collapsed as the airplane was taxiing from landing at the Wood County Airport (1G0), Bowling Green, Ohio. The instructor and student pilot were not injured. The airplane was substantially damaged. The airplane was registered to and operated by Bowling Green State University Flight Center LLC (BGSU), Bowling Green, Ohio, under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as an instructional flight. Visual meteorological conditions (VMC) prevailed at the time of the accident, and no flight plan had been filed. The local flight had just originated from 1G0.

According to the chief pilot and flight instructor, the purpose of the flight was for "employee training." They had planned to remain in the traffic pattern and perform touch and go landings. After takeoff and upon turning onto the downwind leg for runway 28, the pilot activated the landing gear switch to lower the landing gear. The CONT (landing gear control) circuit breaker opened. When the circuit breaker was reset, it immediately opened again, which disabled the gear warning system and landing gear annunciator lights. Maintenance personnel were summoned. Several attempts were made to lower the landing gear. A low pass was made over the runway and the pilots were told that the landing gear appeared to be down. The instructor landed the airplane. As she was turning off the runway, the right main landing gear collapsed. Post-accident examination revealed the rear fuselage bulkhead was cracked.

When the airplane was placed on jacks for retrieval, it was observed that the left main landing gear was not locked. Further examination revealed neither of the main landing gears were down and locked. The school's director of maintenance (DOM) entered the aircraft and used the emergency gear extension. The landing gear dropped into the full down and locked position and the landing gear annunciator lights illuminated.

The airplane was then moved to a hangar for further examination. According to the DOM, the landing gear pump, hydraulic fluid, level, gear warning horns, and lights were checked. No anomalies were noted. With the airplane on jacks, the landing gear was cycled numerous times and operated normally. The circuit breaker remained closed and all landing gear indications were normal. The emergency landing gear extension was also used to verify proper operation and it, too, operated normally.

The flight instructor referenced "the previous grounding maintenance squawk on the aircraft and the current level '3' squawk seeking maintenance feedback on the landing gear." According to the DOM, BGSU utilizes a software product, called SkyManager, to track accounting, maintenance, and flight schedules, among other things. When a maintenance squawk is entered into SkyManager with the aircraft's N-number and a description of the problem, it is given a severity classification of "5" (grounding issue), "3" (non-grounding discrepancy), or "1" (information only).

Examination of the airframe logbook revealed the following six entries pertaining to recent landing gear maintenance:

January 15, 2016 - Replaced nose landing gear up lock switch and switch actuator.

February 5, 2016 - Replaced nose landing gear up lock switch.

March 15, 2016 - Adjusted left main landing gear down lock witch.

April 14, 2016 - Found loose wire on left main landing gear down lock switch. Jacked aircraft, repaired broken wire.

July 19, 2016 - Replaced main landing gear down lock switch and adjusted.

August 24, 2016 - Replaced MLG down indicator switch.

A Federal Aviation Administration (FAA) inspector oversaw the examination of the airplane and noted the following:

"Flight Discrepancy on 08/19/2016: "Gear position lights failed to operate properly." The actual logbook entry on 08/24/2016: 'Replaced MLG down indicator P/N 85315-002. Performed ground (retracted) and flight check (air).' The entry was signed off but did not indicate which gear switch was replaced, just part number. The was also no documentation of the flight in SkyManager.

"Flight Discrepancy on 09/02/2016: 'Landing gear light did not illuminate when gear was put down.'

In SkyManager, the DOM wrote: "Fixed broken wire." No entry was made in the logbook about this discrepancy.

"Flight Discrepancy on 09/12/2016: 'During approach back into Wood Co. my student went to drop. . .'

In SkyManager, the DOM wrote: 'Ground ops check satisfactory. Need feedback.'

"The accident occurred the following day."

The FAA inspector said he found a wire dislodged from the terminal. It did not appear to have been properly crimped because the crimp mark was not well defined. The wire was grounding (shorting) against the landing gear, causing the CNTRL LNDG GEAR circuit breaker to trip open. The DOM said he had pulled the wire out while he was troubleshooting after the accident. The inspector said it appeared the DOM had spliced a new limit switch about six inches from the switch. The wire bundle then passed into the wing. The electrical schematic shows the wire to be energized. The FAA inspector told the DOM that he should make the splice in the wing.

Maintenance personnel re-examined the airplane to determine why the landing gear indication circuit breaker was tripping. According to their report to the FAA, the left main gear down limit switch wire was spliced using the wrong type and gauge of wire. The spliced wires were soldered using heat shrink to cover the splices. The heat shrink did not cover the wires completely. The three wires spliced were bundled together in the left gear well, which allowed the down limit switch wires to short together, causing the landing gear circuit breaker to trip.

The FAA inspector also noted that the flight instructor-chief pilot did not use the emergency checklist completely. According to the checklist, the first step in an emergency gear extension is to cycle the gear. This could not be accomplished because the circuit breaker was open and would not close. The next step is to push down on the emergency gear extension lever (which releases pressure in the hydraulic system and allows the gear to free fall). This was not done. Lastly, the airplane should be yawed abruptly from side to side with the rudder in an attempt to shake the gear loose.

The inspector told the instructor that when advised that the landing gear "appears to be down," it may not be locked "over center." Additionally, the airplane should never be turned with a landing gear issue, but rather it should be kept straight on the runway and brought to a complete stop

NTSB Probable Cause

The pilots’ failure to complete the Emergency Landing Gear Extension checklist and maintenance personnel’s failure to correctly repair spliced wires on the left main landing gear down limit switch, which prevented the pilots from knowing whether the gear was down and locked.