The European Aviation Safety Agency (EASA) today cautioned operators of Sikorsky S-92A helicopters that a recent Sikorsky all operators letter issued in the wake of the Cougar Helicopters S-92A crash on 12 March could appear to suggest using flight manual changes not approved by the US Federal Aviation Administration (FAA), a possibility Sikorsky denies.

Cougar Flight 491, an S-92A with 18 on board, ditched in the Atlantic Ocean off of Newfoundland Thursday morning minutes after reporting issues with the twin-engine heavy helicopter’s main gearbox. Seventeen of the 18 on board were killed.

 Cougar labeled


Sikorsky issued the note on 14 March to update owners on recent safety bulletins related to the S-92A, but not connected with the accident. The letter, provided to Flight International by Sikorsky, reminds operators of all safety bulletins issued in the previous 90 days, including at least one dealing with the main gearbox.

"It is important to be clear that no root cause has been determined," Sikorsky states. "In these circumstances, Sikorsky reminds all operators that compliance with publications including Maintenance Manuals, Operating Manuals, Alert Service Bulletins and Sikorsky Safety Advisories (SSA) is essential."

EASA says a 26 September 2008 SSA (SSA-S92-08-006), not specifically called out in the 14 March letter, informed owners of impending rotorcraft flight manual (RFM) changes for the S-92A based on service difficulties with the aircraft’s main gearbox lubrication system. “This advisory document refers to RFM changes that have not yet been approved by the FAA,” the regulator continues. “In fact, the SSA specifies the ‘corrective action’ as ‘Ensure all flight crews become familiar with the RFM changes when received.’”

Flight has learned that SSA-S92-08-006 discusses methods for detecting and responding to single and multiple indications of main gearbox problems and an impending transmission failure.

EASA says it published today's information bulletin "to ensure that all owners and operators of affected rotorcraft, registered in the European Union member states or associated countries, are aware that the procedures specified (in Sikorsky's September SSA) have not been approved by the FAA or EASA. The relevant emergency procedures in the approved RFM must be observed,” EASA states.

Sikorsky officials tell Flight the 14 March letter was sent to remind operators to comply with existing rules, not proposed changes to the RHM.

"The Sikorsky Safety Advisory referred to in the EASA bulletin (SSA-S92-08-006) had been issued as notice to operators that a change might be forthcoming. Sikorsky's practice is to provide operators with transparency and to supply information as it becomes available.This bulletin was simply notice of a proposed change, with no directive to comply either then or now pending all required approvals per normal procedures," Sikorsky says.