ASN Wikibase Occurrence # 174416
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| Date: | Friday 20 February 2015 |
| Time: | 07:50 |
| Type: |  AgustaWestland AW119 MKII |
| Owner/operator: | Era Helicopters |
| Registration: | N802SM |
| MSN: | 14711 |
| Engine model: | PWC PT6B-37A |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Gulf of Mexico, GM -
 United States of America
|
| Phase: | En route |
| Nature: | Offshore |
| Departure airport: | Houma, LA (HUM) |
| Gulf of Mexico | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The commercial pilot was conducting an on-demand air taxi helicopter flight. The pilot reported that, while in cruise flight over water, the helicopter experienced an abrupt, uncommanded left yaw. The pilot returned to the departure airport and performed a run-on landing. A postflight examination of the helicopter revealed that one of the tail rotor pitch change links (PCL) was fractured.
A review of maintenance records revealed that the fractured PCL had recently been overhauled and installed on the helicopter and that it failed 14.8 flight hours since overhaul. Examination of the PCL revealed that it had fractured due to undetected fatigue cracking that appeared to be the result of bending loads caused by stiff bearings. The stiffness was likely the result of the lack of control of the bearing replacement process.
The PCL bearing replacement procedures, which incorporated rotational torque inspection and bearing staking procedures, were contained in the overhaul manual; these procedures were revised about 3 months before the accident, and the overhaul facility used the revised procedures during the replacement of the PCL. Examination of the PCL revealed that both of the bearings exceeded the maximum allowable rotational torque by at least two times the maximum allowed. Based on the findings of this investigation, the PCL manufacturer corrected the figure in the PCL replacement procedures to display the correct method of inspecting spherical bearing rotational torque.
Probable Cause: The fracture of the tail rotor pitch change link due to excessive bearing rotational friction, which resulted from the bearings being installed in exceedance of the maximum allowable torque during the last overhaul of the pitch change link.
Accident investigation:
 |
|
Sources:
NTSB
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 11-Mar-2015 00:54 | Geno | Added |
| 25-Mar-2015 16:38 | Aerossurance | Updated [Destination airport, Narrative] |
| 22-Sep-2016 16:55 | Aerossurance | Updated [Source, Narrative] |
| 05-Dec-2016 20:44 | Aerossurance | Updated [Time, Source, Narrative] |
| 21-Dec-2016 19:28 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 01-Dec-2017 12:34 | ASN Update Bot | Updated [Operator, Total occupants, Other fatalities, Departure airport, Destination airport, Source, Narrative] |
| 25-Dec-2020 15:23 | harro | Updated [Operator, Nature] |
Corrections or additions? ... Edit this accident description
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