Accident Cessna U206G N16GP,
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ASN Wikibase Occurrence # 210304
 
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Date:Monday 4 September 2017
Time:14:30
Type:Silhouette image of generic C206 model; specific model in this crash may look slightly different    
Cessna U206G
Owner/operator:Private
Registration: N16GP
MSN: U20604467
Year of manufacture:1978
Total airframe hrs:1576 hours
Fatalities:Fatalities: 0 / Occupants: 4
Aircraft damage: Substantial
Category:Accident
Location:Kodiak, AK -   United States of America
Phase: Take off
Nature:Executive
Departure airport:Kodiak, AK (T44)
Destination airport:Kodiak, AK
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The airline transport pilot reported that, while attempting to takeoff in an amphibious, float-equipped airplane in choppy ocean waters, the airplane began to lose speed while simultaneously pitching forward. He subsequently aborted the takeoff, and the airplane struck a large swell, the right forward float strut fractured, the airplane rolled to the right, and the right wing's lift strut was substantially damaged. The pilot's initial examination of the airplane revealed that the left nosewheel was partially deployed even though the landing gear handle was in the "up" position.

Multiple witnesses observed the airplane depart to the east toward an area of unprotected water. One witness reported about 8-ft ocean swells in the unprotected area of the takeoff run, and another witness reported a strong wind from the east. Photos of the accident airplane taken during the rescue indicate rough water near the accident site with large ocean swells. Further, the forecast that day called for 9-ft seas and 25 knot winds. Guidance for takeoffs in float-equipped airplanes states that severe damage can occur when taking off in sea conditions with large swells. Although the pilot was aware of the ocean conditions he still attempted to takeoff in a protected area; however, the airplane did not lift off before reaching the ocean and encountered the large swells.

A postaccident examination of the airplane revealed that the left and right mechanical portion of the landing gear retraction system was improperly rigged, and the amphibious float cable loops were set to an inappropriately low tension load. No evidence of a hydraulic leak was present inside the amphibious floats or the fuselage.

Due to the improperly rigged landing gear, it is likely that the landing gear up-locks disengaged during the impact with the ocean swells. However, neither the pilot nor any of the witnesses reported the airplane yawing about its vertical axis during the takeoff run; thus, it is unlikely that the left nosewheel deployed during the accident airplane's water run. Furthermore, it is likely that the hydraulic lines were breached when the rear float struts were impact damaged, which then released hydraulic pressure and allowed the previously unlocked nosewheel to partially deploy after the accident.

Probable Cause: The pilot's improper decision to takeoff in an area of rough water and ocean swells, which resulted in a failure of the right wing lift strut.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ANC17LA053
Status: Investigation completed
Duration: 7 months
Download report: Final report

Sources:

NTSB

Location

Revision history:

Date/timeContributorUpdates
01-May-2018 13:45 ASN Update Bot Added

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