ASN Wikibase Occurrence # 139364
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| Date: | Wednesday 22 May 1991 |
| Time: | 08:00 |
| Type: |  Bell 47G-5 |
| Owner/operator: | Trent Air Services Ltd |
| Registration: | G-BMDV |
| MSN: | 7944 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | 1 mile NW of Cranfield, Bedfordshire -
 United Kingdom
|
| Phase: | En route |
| Nature: | Training |
| Departure airport: | Cranfield, Bedfordshire (EGTC) |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
CRASH LANDED IN FIELD. A/C DESTROYED. 1 SERIOUS INJURY
Details: FIVE MILES FROM THE AIRFIELD AN AUTOROTATIVE DESCENT WAS MADE FROM 2000FT TO 1500FT, DURING WHICH A CLATTER WAS HEARD BUT NO CHANGE IN ENGINE POWER OCCURRED. A RETURN TO THE AIRFIELD WAS INITIATED & 5MINS LATER THE A/C JOINED THE CIRCUIT AT 1000FT. ON RIGHT BASE A BANG WAS HEARD SO AN IMMEDIATE LANDING WAS INITIATED. FORE & AFT RESTRICTIONS WERE FOUND IN THE CYCLIC CONTROL, ALTHOUGH LATERAL MOVEMENT WAS NORMAL. WITH HYDRAULIC BOOST SELECTED OFF, THE DESCENT CONTINUED USING TWO HANDS TO ACHIEVE CYCLIC MOVEMENT. THE A/C STRUCK THE GROUND AT ABOUT 40KT FORWARD VELOCITY, SLIDING ABOUT 65YDS, BEFORE STOPPING.
THE SKIDS HAD SPLAYED & WERE PERMANENTLY DEFORMED, THE TAIL BOOM SAGGED & THE CABIN AREA WAS DISTORTED. THE MAIN ROTOR MAST HAD PITCHED FORWARD DAMAGING THE BLADES. FUEL TANK FUEL FEED BREAK AWAY FITTINGS PARTIALLY SEPARATED & LEAKS RESULTED, ALTHOUGH THERE WAS NO FIRE. COOLING FAN ASSEMBLY CRANKCASE ATTACHMENT BOLTS HAD FAILED IN HIGH STRAIN FATIGUE, FAN ASSEMBLY MOVED & WEDGED FORE & AFT CYCLIC SERVO. YAW PEDALS JAMMED DUE COLLAPSE OF THE UNDERFLOOR. ONE DRIVE BELT MISSING BUT FOUND SEVERED ALONG WRECKAGE TRAIL. OTHER BELT INTACT ON THE A/C BUT DISPLACED DUE FAN MOVEMENT. BELTS COMPLETED 594HRS (900HR), NORMALLY CHANGED BY OPERATOR AFTER 600HRS. THE FAN DRIVE SHAFT OUTER BEARING HAD BROKEN UP. A/C FLOWN 7HRS SINCE THE LAST 100HR CHECK & LUBRICATION BUT NO EVIDENCE OF GREASE IN BEARINGS OR GREASE CHANNELS. CONSIDERED GREASE HAD LIQUEFIED AS RESULT OF HIGH TEMPS. AEROSHELL 14 GREASE APPROVED FOR USE HAS NORMAL MAX OPERATING TEMP RANGE TO 93DEG C, LIQUEFIED AT 132DEG C. BEARING COMPLETED 1121HRS, SERVICE LIFE OF 1200HRS. BELTS SIGNIFICANT BUT NORMAL SERVICE DETERIORATION.
CAA CLOSURE: RANDOM OCCURRENCE. NO FURTHER CAA ACTION PROPOSED.
Accident investigation:
 |
|
Sources:
1. AAIB: https://assets.digital.cabinet-office.gov.uk/media/542302fae5274a1317000bf3/Bell_47G-5__G-BMDV_09-91.pdf
2. CAA: https://siteapps.caa.co.uk/g-info/rk=BMDV
3. http://www.griffin-helicopters.co.uk/accidentdetails.aspx?accidentkey=14647
4. https://www.pprune.org/rotorheads/419023-rotary-nostalgia-thread-96.html#post7764251
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 21-Oct-2011 07:44 | Dr. John Smith | Added |
| 10-Oct-2012 10:04 | Dr. John Smith | Updated [Cn, Operator, Departure airport, Source, Narrative] |
| 14-Nov-2014 23:36 | Dr. John Smith | Updated [Source, Embed code] |
| 11-Mar-2016 13:56 | Dr.John Smith | Updated [Source] |
Corrections or additions? ... Edit this accident description
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