Author: Colin Gillespie

We discovered that our Scout had a bit of a “bounce” on the ground and decided to do a basic blade track to find out what was wrong.

Oh the joy of being an engineer in the HAAF! After the busiest winter maintenance period on record, we thought we were nearly there. Auster 9 – Serviceable. Sioux – Serviceable. Beaver – Serviceable. Scout – Serviceable. Ahh, no, Scout fuel leak from the sump!

Friday 29th April was a rather different day for some of the HAAF. We were having a visit from members of the Royal Air Squadron (RAS). The visit involved a busy day of flying as we tried to give a Historic Flight to as many as possible, and which also kept the engineers rather busy.

Another week completed. The Sioux completed the airtest and all is good. We fly a full airtest every 3 years so normally that would be the end of that. However, the engine is on condition for calendar life so we will complete a “Power Climb” annually to check the engine performance as well as EFD monitoring of the oil system and external corrosion examination and other checks. A SERVICEABLE Sioux – yeeha. Great work by Kerry and Nick on the Sioux crew.

One aircraft out, next? The Scout looks probable for next out. B1/B2 and B3 maintenance checks completed. Blades x-rayed. Two fuel pumps in the process of replacement. Radio modification underway but causing a few issues with the new loom fit. Bob and Guy are beavering away (wrong aircraft pun) with Phil and Mick playing with the looms.

The Auster 9 had her pre-maintenance ground run on Friday. Straight back into the hangar and an oil drop when warm. Followed by compression checks on the cylinders. Annual maintenance now underway led by Nick.

Dave and Steve are literally beavering away on the Beaver assisted by William. They had a few issues rigging some of the controls so that was a challenge, now overcome. Control checks next and panelling up. We then need a full CAA checkover and full airtest.

Oh Dear – our poorly Chipmunk. Despite fitting a replacement generator and voltage regulator she is still poorly and not playing nicely. Once greenies have capacity after the Scout, there will be much head scratching and playing with electricity. We also have a huge magneto drop to resolve, so no Chipmunk any time soon.

Jay is currently making a new instrument panel for the Auster Mk 1. This is plywood covered in leatherette. The Mk 1 will be worked on as the summer progresses and we have more bodies available.

The HAAF engineering crew are very experienced but looking after 6 different aircraft types is a fun challenge. They all swap between the aircraft quite happily as long as we supply biscuits to refuel at tea break, which is also when the stories begging. An article on the crew may well follow?

Our Sioux, XT131, has had an interesting winter period to say the least! She was due a Primary Service (annual inspection) and some NDT (Non-Destructive Testing). We also found some unexpected issues along the way, which is not unusual when playing with aircraft, certainly of this vintage (just like our engineers).  

A Primary is quite a detailed series of inspections, checks and lubrication tasks. The methods used for conventional NDT include visual testing, penetrant testing, magnetic testing, ultrasonic testing, radiographic testing and eddy current testing, but all share common features in that the materials under test are not harmed in any way. We had to strip the Sioux so we could remove the engine frame and tail rotor blades for testing. So, a great winter had begun.

During the Primary we decided to replace the engine mag plug housing as it has been leaking (when the mag plug is removed) for a few years. On removal, we found a large shard of metal wedged in the plug housing. We believe the metal was from the Freewheel so an investigation was started. During the strip and examine, one of the freewheel springs had a piece missing which matched the shard found. However, further examination of the lower planetary gear drive revealed some of the plastic bearing cages had disintegrated, resulting in the rubbing together of some roller bearings. At this stage, we decided a gearbox replacement was the only option.

So all complete and we have a serviceable Sioux?  Oh, but no. We completed a 30 minute ground run after the gearbox change – all well. But, back in the hangar and a fuel leak from the main fuel supply pipe! So, we have to find a pipe and then complete a 3 yearly full flight test. Watch this space for more news…

The period between mid-November and April is traditionally the maintenance time for our HAAF aircraft. This year was no exception but was to prove a “bit of a challenge”.

It started off by getting an early start on a “major” on the Beaver. Oh dear, that consumed people and patience. Then we started on the Sioux and the Auster Mk 1. The Sioux had issues and the Auster even more. So more people and patience consumed. We solved most of those on the Sioux and decided the Auster Mk 1 was a long term project after all.

Ever the optimists, we began work on the Scout… Oh dear, the effort to improve the radio and intercom was a “bit of a challenge”. Spot the emerging theme?

Oh well, on to the Chipmunk. Ooops, the generator and voltage regulator are not playing, none in stock and getting into the cockpit to remove them is a “bit of a challenge” for old men who don’t fold and bend very easily.

Never mind – we shall start on the Auster 9 and ground run the Chimunk… Ooops, the hangar doors have jammed, cannot get an aircraft out. Another week lost, a “bit of a challenge”.

We lost time because of bad weather. We lost time trying to get some fuel. We lost time for staffing issues (holidays, as if volunteers can have holidays). We lost time because of complexities of aircraft we had forgotten about and had to relearn, a “bit of a challenge”.

This winter has been a “bit of a challenge” but we shall get there and fly the aircraft. That is why we love doing this. After all, where is the fun if it is not a “bit of a challenge”!