Accident Sikorsky S-61N N617CK, Thursday 1 September 2022
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Date:Thursday 1 September 2022
Time:07:35
Type:Silhouette image of generic S61 model; specific model in this crash may look slightly different    
Sikorsky S-61N
Owner/operator:Croman Corporation
Registration: N617CK
MSN: 61164
Year of manufacture:1962
Total airframe hrs:27942 hours
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Substantial
Category:Accident
Location:near Shady Cove, OR -   United States of America
Phase: Take off
Nature:External load operation
Departure airport:Shady Cove, OR
Destination airport:Shady Cove, OR
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
On September 01, 2022, about 0735 Pacific daylight time, a Sikorsky S-61N helicopter, N617CK, sustained substantial damage when it was involved in an accident near White City, Oregon. The two pilots and a ground support team member sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 133 rotorcraft external load flight.

Two days before the accident flight, the helicopter flight crew conducted a timber logging flight. The No.1 engine started without issue, but the No. 2 engine start was aborted after it sustained a hot start, as confirmed by the No. 2 engine T5 temperature digital gauge indication of 999° C, a subsequent indication of --- ° C, and finally 001° C. The engine was allowed to cool, and about five minutes later the PIC started the No. 2 engine without issue, followed by the No. 1 engine; the flight crew then completed an eight-hour flight day.

The helicopter remained in service until the day of the accident. On the day of the accident, while performing their normal logging operation flight, the flight crew heard a loud “bang” twice and decided to make a precautionary landing. With the engines turning, no anomalies were confirmed by maintenance personnel, and they continued flight operations. The flight crew did not perform an out-of-ground-effect hover power check to determine whether they had singleengine capability. After picking up about a 4,000 pound load during climb out of the confined area, another loud “bang” occurred, followed by a series of successive “bangs” that resulted in a vertical descent and hard impact with terrain, which resulted in a subsequent rollover onto the helicopter’s right fuselage.

Postaccident examination of the helicopter’s No. 2 engine revealed overtemperature distress of the gas generator turbine (GGT) section. All stage 1 turbine blades revealed overtemperature distress. Most of the stage 2 turbine blades exhibited deformation about the leading edges and blade tips.During examination, the turbine coupling shaft was unusually difficult to remove, indicative of overtemperature effects, and the turbine forward shaft exhibited a dark blue discoloration indicative of thermal deformation. The metallurgical examination of 11 stage 1 turbine blades revealed evidence of bulk deformation, coating cracking/melting, and creep voiding/surface cracking consistent with overtemperature exposure.

The PIC stated that he did not report the hot start event to the operator’s director of maintenance because he understood a hot start to entail a T5 temperature of 950° C sustained over 2 seconds. However, guidance from the engine manufacturer indicated that hot start criteria are based on a combination of temperature over time, and that hot starts may occur at temperatures of approximately 750° C within about 15 seconds. Given the circumstances of the event and physical evidence from the postaccident engine examination, it is likely that the No. 2 engine hot start that occurred 2 days before the accident contributed to the failure of the stage 1 turbine blades due to overtemperature, which resulted in the No. 2 engine loss of power and subsequent impact with terrain. According to the FAA, serious engine damage occurs if a hot start is allowed to continue.

Probable Cause: A total loss of engine power due to the failure of the No. 2 engine’s stage 1 turbine blades as a result of an unreported hot start two days earlier.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR22LA330
Status: Investigation completed
Duration: 2 years
Download report: Final report

Sources:

https://fireaviation.com/2022/09/05/helicopter-makes-forced-landing-during-logging-operation/

https://data.ntsb.gov/Docket?ProjectID=105847
https://registry.faa.gov/aircraftinquiry/Search/NNumberResult?nNumberTxt=617CK

https://cdn.jetphotos.com/full/5/35576_1611591003.jpg (photo)

History of this aircraft

Other occurrences involving this aircraft

20 March 1985 C-GOKZ Okanagan Helicopters 0 off Owl's Head, Nova Scotia sub

Location

Images:


Photo: NTSB

Revision history:

Date/timeContributorUpdates
06-Sep-2022 00:05 Geno Added
06-Sep-2022 00:23 RobertMB Updated [Total occupants, Location, Source, Narrative, ]
09-Sep-2022 19:48 johnwg Updated [Time, Phase, Narrative, ]
16-Sep-2022 22:23 Captain Adam Updated [Time, Location, Departure airport, Destination airport, Source, Narrative, Category, ]
17-Sep-2024 21:23 Captain Adam Updated [Operator, Location, Phase, Departure airport, Destination airport, Source, Narrative, Accident report, Photo, ]

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