Cessna 172N N74C

Summary

On 2 July 2024 at about 19:00 local time, a Cessna 172N registered N74C was involved in an accident near San Diego, California, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

2 July 2024 at 19:00

Classification

Accident

Location

San Diego, California, United States

Nearest airport

Montgomery-Gibbs Exec (MYF)

Coordinates

32.8157, -117.1396

Aircraft

Cessna 172N

Registration

N74C

Category

Airplane

Year built

1978

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

San Diego → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR24LA229

1 person had minor injuries.

A failure of the No. 2 cylinder due to fatigue cracking as the result of an undersized fillet radius around the edge of the cylinder head dome.

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

Read the full NTSB narrative

The pilot reported that he completed a preflight inspection and engine run-up with no anomalies noted. Shortly after takeoff, while making a right turn from the crosswind to downwind leg of the airport traffic pattern, he heard a loud “pop,” and noticed brown smoke coming from the engine compartment. The airplane began shaking and the engine subsequently lost total power. The pilot declared an emergency and landed on the runway; however, the airplane overran the departure end of the runway and nosed over, resulting in substantial damage to both wings and the engine mount. Postaccident examination of the engine revealed that the No. 2 cylinder head cracked due to an undersized fillet radius around the edge of the dome. The undersized fillet increased local tensile stresses in the head under normal operating loads, which resulted in fatigue crack initiation and growth. The undersized fillet radius was less than that of the mating barrel corner radius, indicating that the undersized fillet was likely machined into the head at the time of manufacture. The remaining three cylinders from the accident engine were examined and revealed a discontinuous fillet in each of the heads that was inconsistent with the manufacturer’s engineering drawings. At the time of the accident, the engine had over 1,400 hours in service in the 4 years since the cylinder was manufactured. The accident engine is likely a relatively high-time engine and could be among the fleet leaders for other engines operating with cylinders manufactured around the same time as the accident cylinders.

Quoted verbatim from the NTSB record.