by Matthew Beres, Airborne Retrofit & Modernization Analyst, Forecast International.
The United Kingdom’s Air Accidents Investigation Branch (AAIB) has released a Special Bulletin regarding an S-92 accident on December 28, 2016, at the North Sea’s West Franklin wellhead platform.
The initial investigation focused on the tail rotor and its components. Immediately, it became apparent that the tail rotor servo piston was damaged. Removing the servo revealed the tail rotor pitch change shaft (TRPCS) double row angular contact bearing to be in a severely distressed condition.
Here’s a breakdown of what happened:
Here’s a breakdown of what’s being done:
The Operator will:
- Review all HUMS data to ensure no anomalies
- Provide fleet-wide borescope inspections
- Require HUMS to be serviceable before flight
- Reduce time between HUMS download/analysis to a five-hour maximum
Sikorsky will:
- Provide a one-time inspection of the TRPCS and bearing assembly for ratcheting, binding, and rough turning
- Compliance is essential and is to be accomplished prior to the next flight from a maintenance facility
- Enforce a three flight-hour limit before return to a maintenance facility
- Require operators under Temporary Revision 45-03 to use S-92 HUMS ground station software to review Tail Rotor Gearbox energy analysis Condition Indicators for alert conditions on a reduced flight-hour interval
- Records in excess of published alert levels will require inspection of the pitch change shaft and bearing
Both the AAIB and Sikorsky are continuing to examine the accident, including the relevant helicopter components. More details will be provided as information becomes available.
Please feel free to use this content with Forecast International and analyst attributions, along with a link to the article. Contact Ray Peterson at +1 (203) 426-0800 or via email at ray.peterson@forecast1.com for additional analysis.
Forecast International’s Airborne Retrofit & Modernization Forecast provides operators in the military and commercial aviation sectors with the information they need to maximize their current investments rather than expand their fleets, a trend that is opening up multiple opportunities for the expansion of retrofit and modernization programs. It offers a one-stop service for tracking the status of commercial and military R&M programs in progress worldwide, and pinpoints key developments in the aviation industry that will impact the market in the future.
A military history enthusiast, Richard began his career at Forecast International as editor of the World Weapons Weekly newsletter. As the Internet became central to defense research, he helped design the company’s Forecast Intelligence Center and now coordinates the FI Market Recap newsletters for clients. He also manages two blogs: Defense & Security Monitor, which covers defense systems and international security issues, and Flight Plan, focused on commercial aviation and space systems.
For more than 30 years, Richard has authored Defense & Aerospace Companies, Volume I (North America) and Volume II (International), providing detailed data on major aerospace and defense contractors. He also edits the International Contractors service, a database tracking all companies involved in programs covered by the FI library. Richard currently serves as Manager of the Information Services Group (ISG), which develops outbound content for both Forecast International and Military Periscope.
