N75EPGrumman Acft Eng Cor-Schweizer G-164A · 1974

On September 18, 2016, about 1440 eastern daylight time, a Grumman G-164A, N75EP, was destroyed when it was involved in an accident near Chestertown, Maryland. The commercial pilot sustained minor injuries. The airplane was operated under the provisions of Title 14 Code of Federal Regulations Part 137 as an aerial application flight.

On September 17th, the day before the accident, the airplane was performing aerial agricultural work when the pilot noticed a significant loss of engine power and made a subsequent emergency landing in a corn field. Maintenance personnel inspected the engine and replaced the No. 2 cylinder, adjusted the valves and test ran the engine; the airplane was subsequently returned to service.

On the day of the accident, the pilot reported that he ran the engine for 15 minutes on the ground then taxied down to the beginning of the private strip and ran the engine near full power for an additional 5 minutes, to make sure everything was normal. Experiencing no anomalies, the pilot conducted a short field takeoff, but immediately after takeoff, when the airplane was just a few feet in the air, he heard a "pop" and felt a vibration, followed by an immediate loss of engine power. The airplane was unable to climb or maintain altitude and it settled back down to the ground. The pilot was unable to maneuver or stop the airplane in time, and it struck farm equipment and a trailer before skidding to a stop and catching fire.

According to airplane maintenance records, the engine was overhauled on July 26, 2011 and the Pratt and Whitney Service Bulletin (SB) No. 1787, dated September 7, 1983, and requisite Airworthiness Directive (AD) No. 99-11-02 was complied with. This included visual and fluorescent penetrant inspection of cylinders for head cracking, and the replacement of cracked cylinders with serviceable parts. Thereafter, repetitive visual inspections of the cylinders must be made every 250 hours for this engine type, a Pratt & Whitney Radial R-1340 with installed baffles. The AD and SB were designed to prevent cylinder head cracking, which could result in engine power loss, forced landing, and damage to the airplane.

Subsequent maintenance inspections on the engine occurred regularly and within the requisite hourly limits set forth in AD 99-11-02. From engine overhaul to the accident (5 years), there were eight documented cylinder inspections in accordance with the AD and in each case, there were no defects noted to the No. 3 cylinder. The most-recent inspection in accordance with the AD occurred on August 21, 2016, at 761 hours SMOH, and about 74 hours before the accident. However, the No. 2 cylinder was replaced twice; once on September 13, 2011 at 112.0 hours total time since major overhaul (SMOH) and again on September 18, 2016 at 835.9 hours total time SMOH, but the reason for replacement was not specified. No other cylinder crack irregularities were noted in the logbook. The entry documenting the most-recent replacement of the number 2 cylinder did not note that an inspection in accordance with the AD had been complied with at that time (nor was one required to have been completed).

Examination of the wreckage revealed that the airplane was taking off from east to west on a private agricultural field that was about 1,000 ft long when it struck a trailer and farm equipment off the end of the takeoff surface, before coming to rest in a large gravel parking area near a hangar. The airplane was impact damaged, the fuselage was consumed by the postimpact fire, and there was significant thermal damage to the engine. Examination of the engine showed that the top of the No. 3 cylinder was fractured and separated near the head of the cylinder. The cylinder was not examined in any further detail.