ASN logo
ASN Wikibase Occurrence # 39234
Last updated: 3 December 2021
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information. If you feel this information is incomplete or incorrect, you can submit corrected information.

Type:Silhouette image of generic S64 model; specific model in this crash may look slightly different
Sikorsky CH-54A (S-64A)
Owner/operator:Silver Bay Logging
Registration: N541SB
MSN: 64-035
Fatalities:Fatalities: 1 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:16 mls NNE of Ketchikan, AK -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:External load operation
Departure airport:Shelter Cove, AK
Destination airport:
Investigating agency: NTSB
The pilot & copilot were on an external load, aero logging operation in a military surplus helicopter, lifting an estimated load of 18,000 lbs. Ground personnel heard a popping sound, then saw the tailrotor begin to slow down as the helicopter began to yaw/spin. It descended to sloping terrain in an area of cut logs. Postcrash exam of the tailrotor drive shaft revealed a separation at the number 5 bearing position. The shaft separation exhibited evidence of high heat & melting of adjoining shaft surfaces. The bearing & its housing were not recovered. The bearing had accrued 505 hrs of service, & was 1 of 2 bearing model numbers that were in use. The bearing was manufactured in 1991, & was purchased by the operator from surplus military supplies. The supplier (of the bearing to the operator) had performed an exterior exam of the bearing & marked 'relubed 10/95' on the bearing box. Exam of the remaining tailrotor drive shaft bearings revealed evidence of low grease fill, water & glycol contamination, & wear patterns consistent with misalignment. In civilian service, the bearing was an 'on condition' part. The operator established a service life of 1,000 hours for aero logging operations. A shelf life for the bearing was not established. The manufacturer indicated the bearing should support a 5 year shelf life. Other operators of the accident helicopter in aero logging reported similar examples of low grease fill & bearing contamination from water in both available models of bearing. CAUSE: failure of the number 5 tailrotor bearing. A factor relating to the accident was: the uneven/steep sloping terrain, where the pilot was forced to land. Possible factors were: inadequate handling/labeling of the 'relubed' bearing by intermediate supplyier(s), and/or insufficient shelf life/service limits for military surplus parts.


Ex CH-54A Tarhe 68-18433 US Army

Revision history:

24-Oct-2008 10:30 ASN archive Added
24-Dec-2009 12:20 TB Updated [Cn, Operator, Other fatalities, Location, Source]
26-Dec-2009 07:33 TB Updated [Aircraft type]
19-Mar-2011 09:36 TB Updated [Time, Location, Source]
21-Dec-2016 19:23 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]

Corrections or additions? ... Edit this accident description