Hughes 369D N5027P

Summary

On 9 July 2023 at about 14:27 local time, a Hughes 369D registered N5027P was involved in an accident near Waldorf, Maryland, United States. 3 people were on board and 3 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

9 July 2023 at 14:27

Classification

Accident

Location

Waldorf, Maryland, United States

Coordinates

38.6175, -77.0011

Aircraft

Hughes 369D

Registration

N5027P

Category

Helicopter

Year built

1981

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Route

Indian Head → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA23LA293

3 people had minor injuries.

Fatigue failure of the overrunning clutch outer race and a subsequent inflight loss of power due to abnormal bending loads as a result of improper reassembly of the clutch subassembly following maintenance and the presence of microcracks on the clutch’s outer race.

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

Read the full NTSB narrative

The flight crew of the helicopter detected an abnormal noise while in cruise flight and the pilot felt a vibration in the collective. The crew chose to discontinue the mission and return to the departure airport; however, about 4 nautical miles from the airport, there was a loud bang/pop noise and the helicopter yawed left. The pilot entered an autorotation and selected a forced landing site adjacent to a pond in a residential area. Home security video captured the final seconds of the flight. The sounds of the helicopter’s engine and the turning main rotor could be heard before the helicopter appeared in the frame, descending steeply in a level attitude. The helicopter dropped from sight behind a house and reappeared just as the helicopter’s nose flared upward and the tail rotor impacted the surface of the pond about the same time. The tailboom was separated by the turning main rotor at or about water contact. The helicopter’s skids impacted the fence that bordered the pond, and the helicopter subsequently came to rest upright. The engine, which continued to run briefly, was shut down by the pilot and the damaged main rotor blades stopped turning. The crewmembers egressed the helicopter without assistance. Examination of the helicopter revealed the overrunning clutch outer race’s splined shaft had fractured, which disconnected engine power from the main transmission. Examination of the fracture surface showed signatures consistent with fatigue. The examination of the disassembled clutch subassembly revealed off-axis and asymmetric wear, indicating that the overrunning clutch was likely reassembled improperly after its last inspection, which occurred about three months and 22 flight hours before the accident. Additionally, secondary microcracks were observed on the shaft portion of the clutch outer race's splined shaft that likely occurred during its manufacture. The improper reassembly of the clutch subassembly following the inspection likely resulted in abnormal loading of the clutch outer race shaft during operation. This abnormal loading, in addition to the preexisting microcracks, initiated fatigue cracking of the clutch outer race, resulting in its failure during the accident flight.

Quoted verbatim from the NTSB record.