Cessna 172 N5550J

Summary

On 17 May 2023 at about 00:12 local time, a Cessna 172 registered N5550J was involved in an accident near Flower Mound, Texas, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 May 2023 at 00:12

Classification

Accident

Location

Flower Mound, Texas, United States

Coordinates

33.0582, -97.2046

Aircraft

Cessna 172

Registration

N5550J

Category

Airplane

Year built

1980

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Denton → Roanoke

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN23LA188

Nobody was injured.

The fatigue failure of the rocker arm which resulted in a partial loss of engine power. Contributing was the airplane operator’s failure to inspect the rocker arm in accordance with the engine manufacturer’s service bulletin.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The flight instructor reported the engine began to run rough and lose power as they descended from cruise flight. Unable to restore full engine power, the instructor performed a forced landing to a field. During the landing the airplane collided with a barbed wire fence and trees, resulting in substantial damage to the wings and fuselage. A postaccident examination of the engine found that one of the rocker arms (p/n LW-15014) had failed. A metallurgical examination revealed a portion of the rocker arm adjacent to the oil squirt hole was pressed inwards in the direction the pushrod drives the rocker arm. Fatigue cracks emanated from the circumference of the oil squirt hole. Rocker arms with similar damage have been observed previously by the engine manufacturer. Lycoming Service Bulletin No. 639 (dated January 17, 2020) details the damage anticipated to the rocker arm oil squirt hole due to contact with the mating pushrod and provides an inspection methodology. Radial cracks are highlighted as warning signs that damage is occurring and once observed, the rocker arm should be replaced. In the subject rocker arm, the missed and/or unaddressed radial cracks likely led to the circumferential fatigue cracking and subsequent failure of the rocker arm and pushrod assembly. The airplane operator was under the impression that the service bulletin only applied to engines overhauled by Lycoming. The service bulletin states that the models affected are “O-320-H2AD, O, LO, TO, LTO-360-E1A6D new, rebuilt, or overhauled engines shipped from Lycoming since June 2017 with less than 500 hours of operation or engines with less than 500 hours of operation since rocker arm replacement.” The service bulletin should then be complied with “at next scheduled oil change, then every 50 hours until 500 hours of engine operation.” The engine had accrued about 173 hours since the overhaul during which the rocker arms were replaced.

Quoted verbatim from the NTSB record.