August 11, 2012


A briefing document by Steven Bentley MD Sofema Aviation Services

Helicopter (Rotary Wing) Maintenance Considerations.

It is a fact of life that Helicopters require far more maintenance per flying hour than fixed wing. The also require extra TLC (tender loving Care !) which translates into the importance of managing competences to the highest standards.

Helicopters require more frequent inspection and lubrication, rigging, and blade tracking.

Cyclic actions inherent to helicopters can cause component or structural fatigue, so NDT plays a significant role in identifying potential flaws before they become critical.

Most of the dynamic components, such as rotor heads, blades, servo cylinders, and swashplates,  have critical maintenance activities associated.

System rigging and adjustments is a critical activity, it is typical that post maintenance flight test take place. It is important that the Maintenance Manual details are followed explicitly and all caution references included in the Work packages.

An important maintenance activity concerns Rotor Blade Tracking – Unless the blades arc in proper track, vibrations will occur in the helicopter which could cause serious structural damage.

Is MSG-3 applicable to Rotary Wing ?

The worlds major aviation regulatory authorities, Federal Aviation Administration (FAA),  European Aviation Safety Agency (EASA) and Transport Canada are all supportive of  the MSG-3 process in general and have given direct support to Bell, during their initial works. Transport Canada and the FAA have already released guidance material requiring the use of an reliability-centered maintenance (RCM) process on all twin-engine helicopters. EASA will release its guidance material very shortly.

MSG-3 came late to the helicopter environment, when compared to their fixed wing cousins. Without doubt Helicopter Maintenance is expensive, so the opportunity to optimize costs is of considerable relevance.

Currently there are only 2 Helicopters which are subject to the MSG-3 process namely the Europ copter EC 175 and the Bell 429 (With Bell being the first).

MSG-3 delivers a reliability-centered maintenance (RCM) approach. MSG-3 optimises the maintenance process so that “appropriate” maintenance is performed. The RCM  approach is a task-oriented process which uses a “top down” approach, effectively  analyzing the various systems to determine failure modes which can contribute to or  cause functional failures, then develops appropriate maintenance tasks as necessary.

Aircraft maintenance moving from MSG-2 to MSG-3 ha delivered savings typically of 15%  to 30 %.

One of the challenges is that MSG-3 was developed for fixed wing so the implementation process has required to be modified to accommodate and adapt to the different needs.

Currently, the following group  (Eurocopter, Sikorsky, Agusta/Westland and Bell Helicopter),  are working on a project  to ensure a common use of terminology and process methodology, to modify/adapt the existing MSG-3 process, and make it more appropriate to the rotary world.

The working group has now had three meetings (with more annual meetings planned) and the way forward is to develop a purely rotorcraft version of MSG-3.

Sofema Aviation Services offer Training in Maintenance Programs and Reliability please visit or email


EASA, FAA, Helicopter Maintenance, MSG-3