ASN Wikibase Occurrence # 237303
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| Date: | Wednesday 24 June 2020 |
| Time: | 12:19 LT |
| Type: |  Bell 407 |
| Owner/operator: | Private |
| Registration: | N120HH |
| MSN: | 53661 |
| Year of manufacture: | 2005 |
| Engine model: | Rolls-Royce M250-C47B |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | near Long Marston, Warwickshire -
 United Kingdom
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Wellsbourne Mountford Aerodrome, Warwickshire |
| Wellsbourne Mountford Aerodrome, Warwickshire | |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot and passenger were returning to Wellsbourne Mountford Aerodrome, Warwickshiree following a short flight over the Malvern hills when the engine failed. The pilot executed an autorotation landing in a field near Long Marston, after which they were both able to exit the helicopter without injury. However, the tail boom was severed during the landing and the helicopter was destroyed by fire.
Conclusion
The investigation concluded that the uncontained failure of the gas producing turbine rotors occurred due to insufficient oil being supplied to the No 8 main engine bearings. The lack of oil was the result of a leak that occurred during the accident flight. Due to the extent of the fire damage to the helicopter it was not possible to establish the source of the leak.
The investigation established that the gas producing rotors were not contained because the engine was not required to be designed or certified to contain such a catastrophic failure.
The uncontained failure resulted in damage to the fuel and oil pipes in the engine compartment, and the leaking fluids ignited in the presence of the hot components. As the helicopter fuel valve remained open, and the booster pumps continued to run after the occupants had left the helicopter, fuel continued to be pumped into the engine compartment
through the damaged component further feeding the fire.
As there was no fire detection system fitted to the helicopter, and because of the extensive fire damage, it was not possible to establish if the helicopter met the fire protection certification requirements. However, the protection offered by the engine bay fire walls enabled the pilot to make a controlled landing and the occupants to safely vacate the helicopter.
Although, the NR was below the speed specified in the RFM during the autorotation, the pilot was able to land safely. The rapid lowering of the collective after landing resulted in a main rotor blade striking and severing the tail boom.
Two Safety Recommendations were made regarding the Failure Mode and Effects Analysis for the engine, and the fire resistance and crashworthiness of aircraft components. The helicopter manufacturer undertook two Safety Actions regarding advice to pilots, and one Safety Action regarding analysis of the airframe fuel filter.
Accident investigation:
 |
|
Sources:
1. https://wmas.nhs.uk/2020/06/24/lucky-escape-after-helicopter-makes-emergency-landing/
2. https://www.flightradar24.com/data/aircraft/n120hh#24c56074
3. https://www.coventrytelegraph.net/news/coventry-news/helicopter-crash-lands-warwickshire-field-18481154
4. https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=120HH
5. https://www.birminghammail.co.uk/news/midlands-news/helicopter-crashes-warwickshire-field-next-18480988
6. Video of burning wreckage: https://www.newsflare.com/video/364466/lucky-escape-for-pair-after-helicopter-crash-lands-in-field-next-to-a-pub
7. http://aerossurance.com/helicopters/b407-rr250-uncontained
Media:
Crews from Alcester, Stratford and @HWFirePebworth were called to deal with a helicopter crash in long Marston this afternoon. Luckily the pilot and one passenger made it to safety before the aircraft caught fire. The crews used hose reels to extinguish the fire along with foam. pic.twitter.com/w82jem46fu
— Warwickshire FRS #StayAlertToStaySafe (@WarksFireRescue) June 24, 2020
Following a short flight the engine of a Bell 407 (N120HH) failed. The pilot executed an autorotation landing in a field, the pilot and passenger exited the helicopter without injury. The helicopter was destroyed by fire, 24 June 2020.
— AAIB (@aaibgovuk) September 30, 2021
Read the report: https://t.co/NzPYcH5Bbx pic.twitter.com/o9ti7fGyB9
Shortly after maintenance a Bell 407 suffered an uncontained engine failure after an apparent engine oil loss. We look at the #AAIB investigation. https://t.co/4uBw0eOGtN #helicopter #accident #flightsafety #aviationsafety #airworthiness #gasturbine pic.twitter.com/k9m9kFrqTv
— Aerossurance (@Aerossurance) November 13, 2021
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 24-Jun-2020 13:39 | gerard57 | Added |
| 24-Jun-2020 13:51 | harro | Updated [Time, Aircraft type, Registration, Cn, Source] |
| 24-Jun-2020 17:42 | Dr. John Smith | Updated [Source, Embed code, Narrative] |
| 24-Jun-2020 17:49 | Dr. John Smith | Updated [Location, Source, Embed code, Narrative] |
| 24-Jun-2020 17:56 | Dr. John Smith | Updated [Source, Embed code] |
| 24-Jun-2020 17:58 | Dr. John Smith | Updated [Destination airport] |
| 24-Jun-2020 21:13 | Aerossurance | Updated [Location] |
| 29-Jul-2020 08:31 | Aerossurance | Updated [Source, Narrative] |
| 30-Sep-2021 19:33 | harro | Updated [Departure airport, Destination airport, Embed code, Narrative, Accident report] |
| 01-Oct-2021 18:11 | Aerossurance | Updated [Embed code, Narrative] |
| 13-Nov-2021 14:26 | Aerossurance | Updated [Departure airport, Destination airport, Embed code, Narrative] |
| 13-Nov-2021 15:36 | Aerossurance | Updated [Source] |
| 13-Nov-2021 15:47 | Aerossurance | Updated [Embed code] |
| 13-Nov-2021 15:47 | Aerossurance | Updated [Phase, Embed code] |
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