Sunday, April 8, 2018

Cessna U206G, N16GP: Accident occurred September 04, 2017 at Trident Basin Seaplane Base (T44), Kodiak, Alaska

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:

Federal Aviation Administration / Flight Standards District Office; Juneau, Alaska

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf


Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

http://registry.faa.gov/N16GP

Aviation Accident Factual Report - National Transportation Safety Board

Location: Kodiak, AK
Accident Number: ANC17LA053
Date & Time: 09/04/2017, 1430 AKD
Registration: N16GP
Aircraft: CESSNA U206G
Aircraft Damage: Substantial
Defining Event: Loss of control on ground
Injuries: 4 None
Flight Conducted Under: Part 91: General Aviation - Business 

On September 4, 2017 about 1430 Alaska daylight time, an amphibious float-equipped Cessna U206 airplane, N16GP, sustained substantial damage while attempting to depart the water at Trident Basin Seaplane Base (T44), Kodiak, Alaska. The airplane was registered to and being operated by the pilot as a 14 Code of Federal Regulations Part 91 visual flight rules flight. The airline transport pilot and three passengers were not injured. Marginal visual meteorological conditions existed and no flight plan had been filed.

According to the pilot during the takeoff run, the airplane encountered small swells and began to lose speed, while simultaneously pitching forward. In an effort to correct for the forward pitching moment, the pilot applied full aft elevator. Shortly thereafter, he aborted the takeoff, but the airplane continued to pitch forward when it was struck by a larger swell. The right forward float strut fractured and the airplane rolled to the right, which resulted in substantial damage to the right wing's lift strut. An initial examination of the airplane by the pilot revealed that the left nose wheel was partially deployed with the landing gear handle in the up position.

A pilot rated witness reported that the accident pilot was talking to several pilots, prior to boarding the airplane, the morning of the accident and specifically asked him "what do you think?" and "which way to go?". He went on to state that one of the options, rather than the typical north departure, was to use "The Cut", which is an easterly departure through a break between the islands. He said this worked as long as the aircraft was airborne before exiting the protected area, as ocean swells were encountered on the other side of the islands.

Another pilot rated witness reported that he leaned out his office door and watched as the accident pilot started his water run. He said his initial thought was that the airplane "must be really heavy" because it took a very long time for the airplane to accelerate onto the step. As the airplane disappeared through "The Cut", he saw the wings start rocking up and down, as the airplane, still on step, encountered the ocean swells on the other side.

A third pilot rated witness reported that he observed the accident airplane begin its water run. He stated that the airplane was in the plow for an estimated 1,100 ft, prior to accelerating onto the step. The airplane then went through the "The Cut" where it encountered about 8-foot-tall ocean swells, and disappeared. He continued to hear the airplane's engine operating at full power for about 15 seconds before it abruptly stopped. He then jumped in his skiff and motored through "The Cut" to the accident site to assist with the rescue of the airplane and its occupants.

A fourth pilot rated witness who aided in the recovery of the airplane the day of the accident reported wind from the east at 15 to 20 knots, 1 to 1 ½ ft seas, with 6 to 8-inch swells. He also stated that there was no evidence of a hydraulic oil leak on the water as the airplane was towed back to the docks at T44.

Neither the pilot, nor any of the multiple witnesses reported the airplane yawing about its vertical axis during the takeoff run.

Photos of the accident airplane taken during the rescue indicate rough water near the accident site with large ocean swells.

The coastal waters forecast for Chiniak Bay on September 4, called for seas of 9 ft, with wind out of the southeast at 25 knots and rain, and a Small Craft Advisory had been issued.

The closest weather reporting facility was Kodiak Airport (PADQ), Kodiak, Alaska, about 4.5 miles southwest of the accident site. At 1428, a METAR from PADQ was reporting, in part: wind 100° at 15 knots; visibility, 4 statute miles, mist; clouds and ceiling, scattered clouds at 1,000 ft, overcast clouds at 3,100 ft; temperature, 54° F; dew point 54° F; altimeter, 29.59 inches of Mercury.

The airplane was equipped with EDO 696-3500 amphibious floats. The hydraulic lines that service the landing gear are routed through the hollow float struts to their attach points on the deck of the floats.

The mechanic who removed the airplane from the water the day after the accident reported that all three of the right float struts were separated completely from their attach points and the hydraulic lines servicing the landing wheels were severed.

A postaccident examination of the airplane revealed that the left and right mechanical portion of the landing gear retraction system was not rigged correctly, and the amphibious float cable loops were set to about a 17-pound tension load. No evidence of a hydraulic leak was present inside the amphibious floats or the fuselage.

The EDO Model 696-3500 Service and Maintenance Manual states in part: "Rig the cable loop to a 75 – 125-pound tension load."

The book, How To Fly Floats, published by EDO Corporation, Rough Water Take-offs states in-part: "When possible, take-offs in rough water should be avoided. Before attempting a rough water take-off, do some reconnaissance of the area first. You may happen to find more favorable surface conditions nearby. Pay special attention to any severe swell conditions that may exist and keep an eye out for swells produced by moving boat traffic. There is a very good possibility that severe damage can be done to either the floats, the attachment gear or the aircraft in big swell conditions." 

Pilot Information

Certificate: Airline Transport
Age: 41, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land; Single-engine Sea
Seat Occupied:  Left
Other Aircraft Rating(s): None
Restraint Used: 3-point
Instrument Rating(s): Airplane
Second Pilot Present:
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification:  Class 1 Without Waivers/Limitations
Last FAA Medical Exam: 05/18/2017
Occupational Pilot: Yes
Last Flight Review or Equivalent: 05/31/2017
Flight Time:  16000 hours (Total, all aircraft), 200 hours (Total, this make and model), 16000 hours (Pilot In Command, all aircraft), 180 hours (Last 90 days, all aircraft), 90 hours (Last 30 days, all aircraft), 0 hours (Last 24 hours, all aircraft) 

Aircraft and Owner/Operator Information

Aircraft Manufacturer: CESSNA
Registration: N16GP
Model/Series: U206G
Aircraft Category: Airplane
Year of Manufacture: 1978
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: U20604467
Landing Gear Type: Amphibian;
Seats:
Date/Type of Last Inspection: 07/01/2017, Annual
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines:
Airframe Total Time: 1576.1 Hours as of last inspection
Engine Manufacturer:
ELT: C91  installed, not activated
Engine Model/Series:
Registered Owner: On file
Rated Power:
Operator:  On file
Operating Certificate(s) Held: None 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: PADQ
Observation Time: 2228 UTC
Distance from Accident Site: 4 Nautical Miles
Direction from Accident Site: 230°
Lowest Cloud Condition: Scattered / 1000 ft agl
Temperature/Dew Point: 12°C / 12°C
Lowest Ceiling: Overcast / 3100 ft agl
Visibility:  4 Miles
Wind Speed/Gusts, Direction: 15 knots, 100°
Visibility (RVR):
Altimeter Setting:  29.59 inches Hg
Visibility (RVV):
Precipitation and Obscuration: Moderate - Mist
Departure Point: Kodiak, AK (T44)
Type of Flight Plan Filed: None
Destination: Kodiak, AK
Type of Clearance: None
Departure Time: 1430 AKD
Type of Airspace: Class G

Airport Information

Airport: TRIDENT BASIN (T44)
Runway Surface Type: Water
Airport Elevation: 0 ft
Runway Surface Condition: Water--choppy
Runway Used: N/A
IFR Approach: None
Runway Length/Width:
VFR Approach/Landing: None

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: 3 None
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 4 None
Latitude, Longitude:  57.780833, -152.391389

NTSB Identification: ANC17LA053
14 CFR Part 91: General Aviation
Accident occurred Monday, September 04, 2017 in Kodiak, AK
Aircraft: CESSNA U206G, registration: N16GP
Injuries: 4 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On September 4, 2017 about 1430 Alaska daylight time, an amphibious float-equipped Cessna U206 airplane, N16GP, sustained substantial damage while attempting to depart the water at Trident Basin Seaplane Base, Kodiak, Alaska. The airplane was registered to and being operated by the pilot as a 14 Code of Federal Regulations Part 91 visual flight rules flight. The certificated airline transport pilot and three passengers were not injured. Marginal visual meteorological conditions existed and no flight plan had been filed. 

In a written statement to the National Transportation Safety Board (NTSB), the pilot stated that during the takeoff run the airplane encountered small swells, and began to lose speed while simultaneously pitching forward. In an effort to correct for the forward pitching moment, the pilot applied full aft elevator. Shortly thereafter, he aborted the takeoff, but the airplane continued to pitch forward when it was struck by a larger swell. The right forward float strut fractured and the airplane rolled to the right, which resulted in substantial damage to the right wing's lift strut. An initial examination of the airplane by the pilot revealed that the left nose wheel was partially deployed with the landing gear handle in the up position. 

The airplane was equipped with EDO 3500 amphibious floats. 

A detailed wreckage examination is pending.

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