ASN Wikibase Occurrence # 239268
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Friday 3 August 2018 |
| Time: | 16:05 |
| Type: |  Brantly B-2 |
| Owner/operator: | Private |
| Registration: | N5901X |
| MSN: | 36 |
| Year of manufacture: | 1960 |
| Total airframe hrs: | 1138 hours |
| Engine model: | Lycoming VO-360-A1AB |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Midland, MI -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Training |
| Departure airport: | Midland, MI (IKW) |
| Midland, MI (IKW) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
After departing from the airport, the helicopter was in a level flight profile about 2,000 ft above ground level, about 1/4 mile south of the airport. The pilot stated that, when the helicopter was about 60 kts and on a heading of about 270°, he felt a “strong flutter” emit from the helicopter and heard a subsequent “bang” from the rear of the helicopter. The helicopter immediately turned 180° to the right, and the pilot reduced collective and maintained control of the helicopter. The pilot increased the airspeed and maneuvered the helicopter for an emergency landing to the departure airport. During the landing sequence, the helicopter experienced a dynamic rollover and impacted terrain.
A postaccident examination revealed that one of the tail rotor blades fractured and separated at the spar. Further, one of the bosses of the tail rotor hub fractured from fatigue. The fatigue crack initiated at multiple sites near the shoulder of the hub shank. These smaller cracks coalesced and propagated inward through over half the hub cross-section. During this propagation, as reverse bending stresses increased, a series of smaller fatigue cracks initiated on the opposite surface, coalescing and propagating inward. When the cracked hub could no longer withstand the stress, the remaining cross-section fractured from overstress. The tail rotor blade affixed to this portion of the hub liberated when the final fracture of the hub boss occurred.
Probable Cause: The in-flight separation of the tail rotor blade due to fatigue, which resulted in the subsequent emergency landing and dynamic rollover.
Accident investigation:
 |
|
Sources:
NTSB
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 09-Aug-2020 07:23 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation