Our Unit Chief Pilot, Mario Carretta, shares an insight into what happens when our AW169 aircraft (Pegasus, aka Peggy) goes for maintenance and the move to having co-pilots as part of our operations.

Aircraft Maintenance

Just like when a car needs a regular service, Peggy needs a prolonged maintenance period every year, or after 400 flying hours, whichever comes sooner. Normally, Wayne Busby, our resident Engineer, carries out routine work in our hangar at Henstridge. However, for more in-depth maintenance, the aircraft is flown to Gloucestershire Airport (Staverton) where our aircraft operators, Specialist Aviation Services (SAS), are based.

While Peggy is away, SAS provides us with a replacement aircraft. This has recently changed from the provision of an MD902 to an AW169, just like Peggy, which means we can provide the exact same level of service throughout the year. At Staverton, the majority of the aircraft’s panels are removed so that a detailed inspection can be made of the aircraft’s structures and components. Repairs and replacement of faulty items can then be made. Improvements are continually being made to the design of the aircraft, so during these maintenance periods, the opportunity is taken to bring the aircraft up to the latest modification standard.

At the time of writing, Peggy is at Staverton and midway through its work package. With the inspections almost complete, work has now commenced to introduce a number of software and hardware changes to bring it up to the latest ‘Phase 6.0’ standard. As well as removing some minor, but irritating nonetheless, software bugs, Phase 6.0 also provides some improvements in aircraft control throughout the speed range.

When Peggy returns, some of the more observant of you will notice a change to the air intakes, as the standard mesh grills are being replaced by Engine Air Particle Separators (EAPS). We have been operating the AW169 for over four years now and the engine manufacturers, Pratt & Whitney, have noticed a faster than expected engine performance degradation over time. This has been put down to the fact that we often have to land on beaches or areas where dust or fine debris can be picked up in the downwash and sucked into the engine, causing premature wear of critical components. The mesh grills are only designed to stop large pieces of debris from entering the engine intake, but by replacing the grill with an EAPS panel, the engines will be much better protected and so will maintain the required performance for longer. Each EAPS panel has a large number of centrifugal tube separators, through which the air passes. Particles are then extracted from the air by centrifugal force, allowing only filtered air to enter the engine, and the particles are then ejected by fans from tubes beneath the EAPS panels.

Once the maintenance period is complete and Peggy is put back together, it will go through a comprehensive series of ground and air tests to check that everything is functioning as expected before it is returned to us for duty.


For over 20 years, DSAA has operated as a single pilot operation. However, in 2021 a decision was made to introduce co-pilots on safety grounds, due, in part, to the increased level of operations at night. With this in mind, five new co-pilots have now joined us with varying levels of experience. They are now fully embedded into our rosters and have fitted in seamlessly. Mark Howard-Smith, Jack Cook and Dan Volpi were SAS employees and already have AW169 and Helicopter Emergency Medical Service (HEMS) experience with other air ambulance charities. Hannah Nobbs and Tom Gee have joined us just after completing a SAS sponsored AW169 type rating and have no previous exposure to HEMS. Hannah and Tom have a lot of hard work ahead of them, as they first get to grips with day operations before moving onto night operations using night vision goggles later in the year.

Read Hannah’s journey to becoming a pilot