NTSB Factual Report

On August 9, 2017, about 1220 eastern daylight time, a Cessna 172S airplane, N5274Q, experienced a loss of engine power while maneuvering at low altitude near Wellston, Ohio. The pilot and passenger sustained minor injuries, and the airplane sustained substantial damage. The airplane was registered to and operated by KCSI Texas, Inc., under the provisions of 14 Code of Federal Regulations Part 91 as an aerial observation flight. Visual meteorological conditions prevailed and a company visual flight rules flight plan had been filed. The flight departed Newark-Heath Airport (VTA), Newark, Ohio, about 1330, and was destined for James A. Rhodes Airport (I43), Jackson, Ohio.

The pilot and observer were conducting an aerial observation flight of a pipeline. While maneuvering toward I43 to refuel, the pilot heard a "significant boom" and noticed a reduction in engine rpm. The pilot unsuccessfully attempted to regain rpm and then initiated a forced landing to a green space between trees. During the forced landing, the airplane impacted rolling, uneven grass terrain, and a barbed wire fence. The airplane sustained substantial damage to the right wing and fuselage.

Examination of the engine by a Federal Aviation Administration (FAA) inspector noted a large hole on the top of the engine crankcase. The airplane was recovered for further examination.

On August 24, 2017, the engine was examined at a recovery facility by a Lycoming Engine representative under the supervision of a FAA inspector. Examination and disassembly of the engine revealed a large hole at the top of the crankcase inboard of the No. 4 cylinder. According to Lycoming Engines, the No. 4 connecting rod failed at the small end bushing. The other 3 connecting rod small end bushings were found displaced forward from their normal positions, and the No. 3 connecting rod small end bushing was free to move by hand.

A review of the aircraft maintenance records revealed the engine was field overhauled on September 2, 2016, at a total time of 2,664.5 hours. During the overhaul, Lycoming LW-13923 connecting rod upper bushings were installed (according to an invoice from Lycoming Engines, the bushings were shipped from the factory on June 30, 2016). The most recent 100-hour inspection was completed on June 15, 2017, at 503.5 hours since major overhaul (SMOH). On July 20, 2017, at 556.4 hours SMOH, the engine oil was changed with no anomalies noted in the oil filter or oil suction screen. The July 2017 oil change record was the last record in the engine logbook.

On August 4, 2017, Lycoming Engines issued mandatory service bulletin (MSB) No. 632B, Identification of Connecting Rods with Non-Conforming Small End Bushings. According to the MSB, LW-13923 connecting rod bushings, shipped between November 18, 2015, and November 15, 2016, may be suspected as not meeting Lycoming Engine specifications and require follow-up corrective action. The MSB stated the following warning, "You must complete the 'required action' in this service bulletin to ensure that your connecting rod bushings are properly seated. If a connecting rod bushing becomes unseated, the connecting rod can fail, causing an uncommanded and complete loss of power." The MSB time of compliance was within the next 10 hours of engine operation.

The FAA issued an airworthiness directive (AD) 2017-16-11, effective August 15, 2017, which required the inspection of connecting rods and replacement of affected connecting rod small end bushings. The AD required accomplishing the instructions in Lycoming Engines MSB No. 623B.

NTSB Probable Cause

The failure of a connecting rod small end bushing, which resulted in a loss of engine power.