ASN Wikibase Occurrence # 235244
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| Date: | Saturday 19 May 2018 |
| Time: | |
| Type: | ICA Brasov IS-29D |
| Owner/operator: | Private |
| Registration: | N38ES |
| MSN: | 38 |
| Year of manufacture: | 1974 |
| Fatalities: | Fatalities: 1 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Avenal, CA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Private |
| Departure airport: | Avenal, CA (CA69) |
| Avenal, CA (CA69) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The private pilot of the glider and his co-owner had jointly purchased the 44-year-old Romanian-manufactured glider, which was last flown about 7 years before the sale. About 3 months after purchase, the pilot completed an annual inspection of the glider. About 2 months later, the glider was moved to the soaring club's home airport, where the pilot and co-owner, with help from a third club member, assembled the glider for the first time. The pilot held a mechanic certificate with airframe, powerplant, and inspection authorization ratings, and was said by colleagues to be a competent and thorough mechanic.
The accident flight was the first flight since assembly. About 1 hour after being towed aloft and released, the pilot indicated via radio that all was well and that he planned to continue flying. There was no further communication from the pilot. When he had not returned about 5 hours later, two club pilots departed to conduct an aerial search and subsequently located the wreckage. Examination of the accident site revealed that both wings separated from the fuselage in-flight and that the pilot had unsuccessfully attempted to parachute to safety. No location or tracking data was available to determine the flight track or altitude history for the flight.
Examination and analysis of the wing attach mechanism revealed that the wings had not been properly installed and secured before the flight. Email and witness information indicated that, during the wing installation, the pilot had some doubt whether he had properly secured the wings and had called the previous owner of the glider to obtain his input. The pilot's conclusion from that conversation was that the wings were secured properly and that no additional action was needed. Although some of the attach hardware did not appear to be in accordance with the manufacturer's parts catalog, which may have interfered with the installation of the wings, the effect of this hardware on the installation process could not ultimately be determined. Access to the attach mechanism during wing installation was via an approximate 2-inch diameter cutout in the fuselage skin, which provided a partial view of the assembly when installed. With basic knowledge of the wing securing design and mechanism, the pilot should have been able to readily discern whether proper wing security had been achieved.
Both individuals who assisted with the wing installation reported that they did not recall any abnormalities or indications of significant difficulty with the process. They both reported that a post-installation functional check of the flight controls was satisfactory; however, the flight control system design was such that the fuselage-to-wing control link connections could be successfully made despite the improper installation of the wings. This likely provided the pilot a false positive indication of the integrity of the wing installation, reinforcing his conclusion that the wings were properly installed. Despite the incomplete and incorrect assembly, the friction resulting from the partial engagement of the attach mechanism was sufficient to hold the wings in place for at least an hour of flight.
Several factors decreased the potential for ensuring that the wings were properly installed and secured; the manufacturer no longer produced or supported any gliders, precluding any direct assistance to the pilot/co-owner; the only written assembly guidance available was of poor visual and technical quality and provided only generic assembly information in poorly-translated text; and the previous owner did not live nearby and there were only two other of the manufacturer's gliders registered in the US, which significantly limited alternate information sources for the pilot.
Despite the scarcity of accessible, quality assembly guidance, with the wings uninstalled, a person could access and operate the attach mechanism to determine proper assembly indications. There was no evidence that the pilot or either of the other two persons who helped install the wings ever conducted such an ex
Probable Cause: The pilot's improper installation of the wings onto the glider, which resulted in an in-flight wing separation. Contributing to the accident were the pilot's limited familiarity with the design and a lack of reliable assembly guidance.
Accident investigation:
 |
|
Sources:
NTSB
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 19-Apr-2020 17:25 | ASN Update Bot | Added |
| 24-Dec-2021 18:11 | harro | Updated [Accident report] |
Corrections or additions? ... Edit this accident description
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