ASN Wikibase Occurrence # 374851
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| Date: | Wednesday 18 June 1986 |
| Time: | 09:55 LT |
| Type: |  Aerospatiale AS-355F-1 |
| Owner/operator: | Petroleum Helicopters, Inc. |
| Registration: | N5796T |
| MSN: | 5166 |
| Total airframe hrs: | 3500 hours |
| Engine model: | Allison 250-C20F |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Galveston, TX -
 United States of America
|
| Phase: | Approach |
| Nature: | Ferry/positioning |
| Departure airport: | High Island 571, TX |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
THE PLT RPRTD THAT WHILE APCHG AN OIL DRILLING PLATFORM FOR A LNDG, HE OBSERVED THE MAIN ROTOR BLADES GO OUT OF TRACK ABOUT 8 TO 10 INCHES. HE ALSO RPRTD THE HELICOPTER DEVELOPED A 1:1 VERTICAL VIBRATION. DRG THE LNDG, THE HELICOPTER ENTERED INTO GROUND RESONANCE & THE PLT IMMEDIATELY SHUT DOWN BOTH ENGINES. AN EXAM OF THE HELICOPTER REVEALED THE LEFT FORWARD TRANSMISSION SUPPORT BAR (TSB) WAS BUCKLED & CRACKED AT MIDSPAN. A METALLURGICAL EXAM OF THE FRACTURE AREA ON THE TSB REVEALED EXTENSIVE, LOW CYCLE, HIGH AMPLITUDE, FATIGUE CRACKING. THERE WAS EVIDENCE THAT THE PROPAGATION TIME OFTHE FATIGUE OCCURRED OVR ABOUT 5 HRS OF OPN. THE INV DID NOT REVEAL WHEN THE ORIGINAL BUCKLING OF THE TSB OCCURRED. NO HISTORY OF A PREV HARD LNDG OR GND REASONANCE WAS FND. ALSO, THE RED ARM OF THE STARFLEX HAD FAILED; AN EXAM INDCD IT HAD RUPTURED EITHER UNDER STATIC LOADS, OR VERY RAPIDLY UNDER HI DYNAMIC LOADS. WHEN TESTED, EXTN & RETRACTION TIMES OF LNDG GEAR DAMPERS WERE 8.34 TO 10.38 SEC; AFTER ACDNT, TIME LMTS ESTABLISHED AT 6 TO 13 SEC, PREVIOUSLY 11.1 TO 13.1 SEC
Probable Cause:
Accident investigation:
 |
|
Sources:
NTSB LAX86MA268
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 28-Mar-2024 13:35 | ASN Update Bot | Added |
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