ASN Wikibase Occurrence # 278627
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| Date: | Friday 23 July 2021 |
| Time: | 15:10 LT |
| Type: |  Piper PA-14 Family Cruiser |
| Owner/operator: | Private |
| Registration: | N4206H |
| MSN: | 14-9 |
| Year of manufacture: | 1948 |
| Total airframe hrs: | 2691 hours |
| Engine model: | Lycoming O-320 SERIES |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | 15 mls SE of Anchorage, Alaska -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Private |
| Departure airport: | Anchorage-Lake Hood, AK (LHD/PALH) |
| Anchorage-Lake Hood, AK (LHD/PALH) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
A float-equipped Piper PA-14 airplane, N4206H, sustained substantial damage when it’s rudder structurally failed in flight about 15 miles southeast of Anchorage, Alaska.
The pilot reported that while in level cruise flight, frequent left and right rudder inputs were required to keep the inclinometer centered, similar to a light turbulence encounter. The airplane then began to experience a constant yaw, with elevator adjustments required to maintain level flight. He stated that the oscillation then stopped and a 'very large right rudder input' was required to maintain the course heading. The pilot was able to maintain control of the airplane and land uneventfully.
An initial examination of the rudder revealed that the vertical spar tube separated above the upper hinge point and the top portion of the rudder folded over the horizontal stabilizer tail brace wires. Further examination of the accident airplane's rudder post found radial features with crack arrest lines, consistent with fatigue from multiple origins at the outer diameter. The piece of post from the upper side of the fracture was further examined using a scanning electron microscope. Multiple fatigue origins were identified on the right side that originated from corrosion pits on the exterior surface. Fatigue fracture features were identified around approximately 1/4 of the circumference on the right side, but the total extent of fatigue cracking could not be determined conclusively due to post-fracture contact damage on the surfaces.
Analysis of the rudder post's material composition found it to be consistent with Piper part number 40622. According to engineering drawings, part number 40622 rudder posts were originally manufactured from American Iron and Steel Institute (AISI) 1025 carbon steel. A Piper engineering change order specified a change to AISI 4130 low-alloy steel that was incorporated into the part number 40622 engineering drawing in June 1974. According to Advisory Circular 23-27, Parts and Materials Substitution for Vintage Aircraft, AISI 4130 low
Accident investigation:
 |
|
Sources:
NTSB ANC21LA064
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 01-Jun-2022 10:35 | ASN Update Bot | Added |
| 27-Nov-2023 20:16 | harro | Updated [Aircraft type, Operator, Other fatalities, Location, Departure airport, Destination airport, Narrative] |
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