Cessna U206G N16GP

Summary

On 4 September 2017 at about 22:30 local time, a Cessna U206G registered N16GP was involved in an accident near Kodiak, Alaska, United States. 4 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

4 September 2017 at 22:30

Classification

Accident

Location

Kodiak, Alaska, United States

Nearest airport

Trident Basin (T44)

Coordinates

57.7808, -152.3914

Aircraft

Cessna U206G

Registration

N16GP

Category

Airplane

Year built

1978

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Kodiak → Kodiak

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ANC17LA053

Nobody was injured.

***This probable cause was modified on November 27, 2018. Please see the docket for this accident to view the original 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 float struts.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB 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.

Quoted verbatim from the NTSB record.