20/02/2010 One of '655's Olympus Engines Undergoes Deep Examination

As our regular visitors and members will have heard, we have decided to 'drop' one of our Bristol Olympus 301 engines from the aircraft in order to carry out a detailed examination of the low pressure (LP) and high pressure (HP) compressor rotor and stator blades. This has come about because of a concern voiced by Rolls Royce last year that there is a chance that corrosion in those parts of the engine could lead to engine failure and possible release of high-energy debris from the engine and airframe. Obviously as responsible operators of an ex-military aircraft, we are always very mindful of potential risks and we seek to mitigate for any identified risk before we ever consider any operation of the aircraft. So with all this in mind we have decided on action ;that we believe fully complies with Rolls Royce's recommendation that 'special inspections using non-standard inspection tools and techniques' be carried out on our oldest engine before we consider operating the aircraft again.

The No 4 engine (starboard wing, outboard position) is the engine we have selected based on its number of operating hours. Our view is that whatever we find on this engine will represent the worst that we can expect from any of the other three engines. We can also use the opportunity to address another known defect - we know that there are two 0-stage stator blades that have small stress cracks in them (this type of small crack was a known design weakness only in the 301 variant of the engine) and with the engine removed and partially disassembled, it makes perfect sense to replace the two blades with good spares from our 'seized' engine obtained last year from our friends at Woodford.

So it was that in the last week of January we embarked on this mammoth task. Here is the story, so far, in pictures:

The three engine doors are firstly removed and placed out of the way	Four chain hoists are fitted to the lifting points at the four corners of the engine - the two front hoists are seen here (linked with a special 301 adapter). The engine weighs 2.5 tonnes	The 'A-frame' affixed to the front of the engine provides the fixing for the front hoists
It's a tight squeeze for Eric ("sooty") in the engine intake!	We selected two team members with long arms and short necks to remove the pip pins from the main trunnions	Final touches are made to the engine stand by Richard
Whilst lowering, the CSDU electrical connections need to be watched for hang-ups	The engine is almost clear of the airframe	When it was clear of the airframe, the stand was positioned underneath
Richard watching that the trunnion locates correctly on the stand	One empty engine bay  looking aft	The empty engine bay looking forward to the intake
We had a visitor arrive just as we were lowering the engine - Mark Alcock, our long-service Crew Chief who had recently damaged his knee during the bad spell of weather	A hubbub of activity dismantling the 'plumbing' around the front of the engine	The three engine doors are refitted whilst the engine is temporarily out of the airframe

The lifting beam in place to remove the top half of the LP compressor casing

The lift starts	Easy does it!
Everyone is keen to have a first look inside the compressor	The top half of the compressor casing, with the stator blades clearly illustrated is carefully lifted clear of the engine by Roger aka "Bovril"	The LP rotor blades are now all very visible - and the good news is that the rotors and stators are immaculate, if a little dirty. No corrosion, just a little lacquer displacement
The LP compressor rotor blades after a good clean	The LP compressor stator blades after a good clean	Dave starts to remove all the loose paint from the intake end of the engine bay
Dave applies an alloy primer to the front of the engine bay	One of the two 0-stage stator blades which we took the opportunity to replace	The special tool to extricate the stator blades from the dovetail groove in the casing

We will bring you further updates week-by-week....

The next stage, a touch-up of the lacquer on the LP blades, then put the LP compressor back together and move on to the HP compressor and do the whole thing again! Still, it keeps us off the streets!