It all started with a phone call from our Andy Green to Graham Stokes, the facility manager at The Glen Engine Test House, DRA Pyestock near Farnborough. He inquired as to whether the "Sea Level Bed" would be suitable for balancing our Spey 202 Hybrids. This initial phone call was placed late on Thursday 20th June and a deal was struck with DRA by the following Monday - this gave the green light to what was to prove to be an "unusual" two weeks.
Graham Stokes and his gallant test team of Mick Dyes, Tim Cannon, Ed Mansfield and Steve Meredith all sprang into a frenzy at the thought of being let loose on a pure Spey. I should mention at this time that the "Glen" bed is normally employed for Engine Controls Technology of all types, normally using Spey engines as a base for these unusual tests, although not normally not in reheat. Graham's team consists of highly skilled individuals pulling as a very efficient team.
Well, that's enough of the PR. On Tuesday 25th the Glen team removed their current "test engine" and installed the first of the two Hybrids (partially modified 202's). Taking a little over 24 hours to complete the transition is a tremendous feat considering the amount of work required to "bed" an engine: blanks to manufacture, controls to modify, set and finally test. By Wednesday afternoon they were ready to turn and burn!
However, due to circumstances beyond our control, tests could not start until the coming Monday - 1st July.
In this time Nigel Bourne, our tame Rolls-Royce representative, went to find himself a humble abode to rest his weary head for the time he would be spending with us. This he soon found, (which just happened to have a Jacuzzi - or so we were to hear all week). Meanwhile Steve Wiltshire, the Thrust SSC engine team hippie, took his wigwam and found himself a quiet campsite with en-suite rain and the odd puddle to bathe in. "Just as adequate," you may hear the Rolls-Royce rep say? However, yet again I digress!
Nigel Bourne was present for the initial running tests and was supplied with all the relevant data required, which when processed would help to balance the engine with the second when it was run later. This would appear to be Nigel's first experience of a Spey in full reheat. When asked for a comment, "Yeah, scarey isn't it?" was the reaction.
During further tests, the engine experienced a limited amount of afterburner instability, especially in midrange. This gave the team a bit of headscatching experience. After some trial tweaks Graham traced the problem to a section of the data collection and processing equipment. This was being affected by the reheat air resonance. Although Graham and his team felt this was the source of the problem, they wanted to be sure by checking that the other engine reacted as this did. The Thrust Thermodynamic Specialists, ("sumpies") were happy with this and this problem apart were very happy with the condition of the engine and its thrust rating.
Graham's team commenced the engine swap, ably assisted by Steve Wiltshire of wigwam fame and Nigel from Rolls Royce (they do get their hands dirty, honest, guv!). Nigel did a sterling job thanks!
With the engine swap completed by midday - another fine achievement by the Glen team - we were nearly ready to go. However, during the final throttle rigging checks, a major problem appeared in the engine throttle linkage ("cambox" to the anorak brigade). This would necessitate a cambox replacement, which is not very high on this list of Spey technicians' "favourite things to do when you're bored" list. Yet again the Glen team came up with the goods and appeared with a cambox on loan. I arrived on the scene just at the wrong time and everyone was extremely happy to hand it over to me! Steve Wiltshire and I started it off, but he then had to leave us for a few days so the Glen team and I continued the job.
Graham's team helped me finish the cambox change, enthusiasm dripping from every pore, or was that sweat? By 4 p.m. we were ready to run. The team completed the preliminary runs with no leaks, well, maybe only one little one. Perhaps I should have tightened the pipe up properly, as I was reminded repeatedly for the next few minutes. With the fuel leak cured, Richard Noble turned up just in time to see the reheat handling checks. Impressed? I should say so. The instability observed with the initial engine was similar so this virtually proved Grahams theory (smart people these test bed peeps). However, a fuel leak appeared in the Pressure Ratio Control Unit (reheat ejector nozzle control unit, for the anoraks). Heads were getting red raw with scratching. I then departed to assist Queen and Country, leaving the others to manage until an answer was found. Although Nigel had returned home on Wednesday, Tim from the test bed was able to supply Rolls Royce with the relevant steady state data required to carry out balancing calculations.
Steve Wiltshire and Nick Cooper arrived to help the Glen team scratch their heads over the PRCU leak. It then came to light that such was the teams concern over the throttle problems, that Graham's wife found him "fixing" the throttles at the top of their stairs at 3 a.m. one morning, and Ed even had a strange wardrobe experience which will remain a secret to only you and me!
Steve and Nick solved the fuel leak, and no it wasn't my fault - this time. Runs were resumed. Unfortunately the engine seemed to be holding the reheat flame lit, well down after deselection. Heads were getting sore again.
The Thrust team decided to check the engine throttle rigging and sure enough the reheat rigging was out of limits. A reheat system re-rig, done with a Haynes manual and a great deal of memory extraction proved fruitful. This allowed us to run the engine within the time constraints I had set. Graham started the engine and "Yippeeeeee!" - the system worked well and all were happy.
As Graham was running out of coffee again it was decided that the job was now complete and we had better let these nice gentlemen get back to their work.
With the job done this only leaves me to thank DRA / DERA and particularly Graham Stokes and his band for a fantastic effort. He managed to stay within budget and also provide us with a team of pure professionals capable of completing a great deal of work in an extremely short space of time. Thanks, guys!.
Only one or two questions remain unanswered:
Thanks for giving us "The Glen Experience". This gives the Thrust team the confidence of two healthy, balanced engines.
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