Jaguar - Adour Mk106 Experience
 

Near the end of the Jag's service in the RAF, the aircraft were upgraded with Mk106 Adours. I seen some comments on the net (and here) that this version of the Adour was less than sucessful. I'm curious if any former pilots or maintainers lurking about have any specific details of what problems were encountered or if the engine performance lived up to it's claims.

Thanks

Mark

The reason the 106 eventually got funding was not because of increased performance but increased reliability. Unfortunately everybody expected a big increase in thrust, but that was only a modest by-product of the work that RR carried out (and which was more or less offset by the increased weight of the engine and its airframe mods at the back which had to be balanced by additional ballast in the nose, can't recall precise numbers but an increase of 200kg to the basic mass comes to mind). In answer to your question as far as reliability was concerned it was probably better than the 104 in terms of reliability as it matured but there were a few gotcha's which had to be learned about on the way. As for thrust, probably about the same, although I think accel times and handling should have been a bit better than the 104- perhaps one of the pilots will answer that bit, plenty of ex Jag guys look in here.

Frankly I think that any efforts to improve the performance of a thinly disguised APU should be applauded.

Kitbag is 100% correct in that the 106 only gave a modest increase in thrust (5% - up to the amazing figure of 5514lbf dry and 8245lbf reheated;)) and that this in itself was a fortunate byproduct of an attempt to increase overall reliability and improve specific fuel consumption.

The 106 used proven components from 3 existing Adour engines, namely the Mk871 fitted to the Goshawk (Engine core) the Mk811 fitted to the Jag International (Reheat system) and the existing Mk104 (Accessories, filter packs, gearboxes)..... Unfortunately, good ideas like this rarely work out trouble free in practise, and the 106 brought with it its own problems.

The 106 suffered badly from rear end burnouts and shedding of the turbines. There were several potentially catastrophic instances of this burnout occurring, with one failure exiting the engine casing and missing the F4 fuel tanks above the engines by mm. Several different attempts at curing this were tried by RR, including a heat resistant spray coating applied to the insides of the jet pipes, 'anvils' being attached to the reheat spray rings and vapour gutters to prevent unburnt fuel build up, and several others. Unfortunately none of these completely cured the problem, and the issues dogged the Jaguar until its exit from service, with all engine issues being directed immediately to RR for investigation.

As far as maintainability of the 106's goes, this was much improved with the introduction of a digital control system, and the DECATS facility. However, losing the ability to make any flight line adjustments of the Fuel Control units, was a bit of a PITA.

Hope that answers a few questions for you.


Flipflopman

Adour Mk106
 

I would like confirm or challenge the comments in the associated threads

The Mk106 was a maintenance spend to save programme - improved reliabilty. The engine was derated to meet this requirement, albeit the derated engine gave more thrust than the Mk104.

The Mk106 was a direct replacment for the Mk104 - minimum changes to aircraft to accommodate the engine

Regards weight and ballast. The ballast modification was necessary to address a number issues and not just the engine. During the life of the aircraft CofG had moved aft (changes in weapons fit and airframe modifications). I some configurtations the Mk104 aircraft was operating beyond the aft CofG limit. Hence, the opportunity was taken to address all the CofG issues concurrent with fitting the heavier Mk106 engine.

There were no turbine failures.

The core engine exceeded the reliability targets and the expected saving in engine maintenance was achieved. As far as I can recall no engines were ever changed for core engine problems (excluding FOD).

There were a few incidents of heat damage to components in the reheat module (Module 12). This problem was known and understood but there were no funds available to introduce a full length heat shield within the jet pipe.


The feedback I had from Pilots was excellent.
Even with the few reheat damage incidents, there was still a stepped improvement in reliability.

Gibsonsj,

Agree totally with your post regarding the other issues :ok:, however, turbine failures did occur in the 106, such as in this case of a 41 sqn aircraft shedding its LP turbine in Feb 05. I was at Colt at the time and witnessed the damage personally after it was returned to the hangar. :eek:

http://k43.pbase.com/u49/stevieb/upl...ameOutcopy.jpg


Flipflopman

The Adour 106 was conceived from a marriage of the US F405, a new digital control and the reheat system taken from the Mk411.
The dry engine exhibited all the promised reliability charactaristics that the USN have experienced over the years with the T45 operation :ok:(there were certainly no issues with the turbine as suggested in a previous thread).
The digital control gave many advantages over previous Mks of Adour, there was no setting up to worry about, and the engine could be tuned around the flight envelope for maximum benefit.
There were issues with the reheat system, but all had an identified fix. Sadly there was not the time or money to embody them.
Given a kinder roll of the dice the 106 Jag could have been an extremely effective tool in today's environment.

I agree with Sleeve Valve, and I too wasn't aware of any turbine failures. There were some re-heat issues but I believe there were fixes for them all but sadly no RAF will to implement them due to the out of service date (so no operational impact I guess). I hugely enjoyed flying the Jag and the engine never let me down http://images.ibsrv.net/ibsrv/res/sr...ies/thumbs.gif, the 106 had a thrust increase (5% ish), a reduced sfc and the engineers seemed really happy with it:D (as much as gingerbeers ever are).

Why you asking?

APUs
 

Flap 62, I guess you would say that wouldn't you (being a Harrier pilot and all that) at least Jag pilot's stop whining after the engine shuts down! http://images.ibsrv.net/ibsrv/res/sr...lies/wink2.gif

Stops whining?
 

Unless you left the EHP switched on of course!
BV:eek::ok:

PTR, it is perhaps just as well you didn't have any in-flight engine shut downs. During the initial introduction into service GR (XZ400) had serious issues in getting through the relight performance at the edge of the envelope. The AMF sooties who were dealing with the aircraft went through some pretty painful times as the UTP/STANEVAL S/L Jim ##### (can't remember his surname, but a real gent who did his utmost to get this thing working) just couldn't in all conscience sign it off. I clearly recall a conference call with RR were the answer was we know- it either starts on the ground, or it starts in the air, you won't get both.

As best as I recall the 41 incident was due to unstable reheat flame burning through the side of the jetpipe. I think the cause on that one was attributed to damage (whether mechanical or thermal) to the Mo12 reheat manifold assy. Certainly the proximity of the damage to the rear group was uncomfortable and potentially catastrophic. An inspection regime and tight limits were put in place to detect further faults before they got too bad.

Wonder what the airworthiness guru's would make of a design where fuel tanks surround the rapidly rotating hot components of gas turbine engines?

In answering Mark's original question, I have to agree with Gibsonj and flipflopman's generally positive assessments of the 106 which both offer more technical detail than I ever could without reference to notes. As a Jag pilot with over 2000 hrs on the jet and a fair amount of time with the 106 I have to say that as far as I was aware, the vast majority of the Colt guys thought it was improvement on the old 104. We knew from the outset that we weren't going to delivered bags more thrust for all the reasons that have been laid out in previous comments - predominately driven by the requirement to derate the engines on to provide the 'spend to save' financial justification for the upgrade. I think I can recall 2 fairly significant rear end issues with the 106 (already covered) but as both happened to 41 sqn aircraft which were both being flown by QFIs at the time the problem may not be entirely down to the engine. I don't know what the 106 serviceability stats were but I suspect that (excluding bird strikes) the Jag sooties spent far fewer nights away recovering sick jets than their Harrier or Tornado mates.

No surprise to see that Bob the Viking's still skiving off during the working day!

A view from one of the RAF test pilots - not the one who now works for RR, by the way
 

Chaps

I was one of the test pilots who did the trial on the new engine, and I don't now work for RR! I reply here because there seems to be some 'data' discussed based upon single-incident memories or recalled problems. Statistically this puts the 106 in a poor light and I agree with Sticktop Latearm in that the guys thought it was an improvement.

From my recall, the engine had a much greater thrust potential than the installed RAF fit, but I've forgotten the exact figures. On a practical level the reduced thrust allowed mixed fleet operation whilst it improved engine life.

The 106 was as robust as anything previously installed - which by the standards of many other engines in service is bomb proof (I've flown over 12 other modern fast jets that cause the pilots palpitations if the engine coughs). During the trial and subsequently when I operated the Jag with the 106, I was completely happy with the relight/light-up. The phrase in the thread that alludes to 'either lights up on the ground or in the air, but not both' sounds utter fantasy. This simply is not true.

Let's be careful that one instance of a remembered event does not detract from the truth that the Adours are very, very reliable work horse engines still operated with great confidence in many corners. The quote in SL's relpy sums it up for me:

'I don't know what the 106 serviceability stats were but I suspect that (excluding bird strikes) the Jag sooties spent far fewer nights away recovering sick jets than their Harrier or Tornado mates.'

WIL (first post on PPrune for years, but couldn't see this one drag on without comment)

How many hours did the Mk106s have on them when the Cat was retired? Have they been recycled into the Mk821 version being offered to India to compete against the Honeywell F125NI, or is the Mk821 a different beast altogether?

I/C

Sticktop Laterarm
 

Cheeky bugger!
Fair point though.
BV:E

Reading WIL's comments and then Ian Coriggible's make me wonder why someone from UA (should that be USA) is asking about if the Jag engine was unreliable. From what I understand, speaking to a friend still serving in the Indian Air Force and ex Jag eng officer to boot, that there is a big fight between Rolls (UK) and Honeywell (USA or is that UA) to re-engine the Jag that is STILL being built by the Indians under licence (they must like it!). What I have been told is the new Adour is the core of the engine being used in the Hawks now going to India with upgraded bits bolted on. I understand Honeywell are taking an engine that only saw use in a fairly unsuccessful far east trainer and trying to shoe horn it into an aircraft not designed for it (and my BAe mate says all the wind tunnel data is no longer available). Being a Brit, and patriotic, I know who I want to get the contract and surely (don't call me surely!!) the Honeywell option has got disaster written all over it. As WIL says, are the RAF memories just focusing on the one off events. Anybody know more about the whole re-engine contract? The original question just sounded odd to me!!!!!

Double D,

No ulterior motive on my part - I was just interested as to what came of the investment in the Mk106, given how late in Jaguar's service it arrived. I have a vision of row upon row of Adours lying in a warehouse somewhere in Avon, being stripped of their precious metals by the local scrotes, as happened with the ex-Phantom Speys. (Allegedly... :E)

I/C

Nice to see a bit of Jag v Harrier banter again!:ok:

IIRC this is RL coming back in to land.............:eek: :D

http://i58.photobucket.com/albums/g2...tishall_o2.jpg

Mk106 in use at Cosford in GIA.

"Nice to see a bit of Jag v Harrier banter again!"

There's a lot of that going on in my office at the moment!