mjrMerlin-engined Halifax (100% certain about that) so probably Lancaster too.
Have you got the actual pump? That bit is just the electric motor that drives the pump.
Many thanks CR, that is grand. Yes I have the pump, but unfortunately the motor armature and comm are corroded beyond repair. I am looking for a replacement motor, so now I know what it came from I can keep an eye out.
mjrI think that everyone is panicking to early, Yes there is a draft MPD that has come out and if everyone reads it you will see that it is open to discussion for companies to come back with what can be done to prevent the engines from failing. If you think back a number of years, a similar thing happened on the Avon engine that was going to finish the Hunter but the companies operating the aircraft came up with a solution in MPD 2001-001 which allowed the Avon to carry on. That was more serious than this present draft as it involved the actual core of the engine. This draft is to do with the fuel system that is an accessory and can be changed on the engine. I think that everyone should stop slating the CAA over this. At the moment as they are giving the operators of these engines a chance to come up with a solution to keep the aircraft flying and i for one am very confident that this is going to happen. I have been with a CAA surveyor for the last two days and i can assure you that they are willing to listen to solutions. As for St Athan we have diversed into other areas of aviation because we saw the decline in airshows a few years ago but we will still do our utmost to keep a selection of ex military jets flying and working with other companies who feel the same that the day of the Hunter, Jet Provost Gnat etc is far from over.
NAD, you will see that not a single poster has ‘slated the CAA’, in fact quite the opposite, why would anyone do that? The proposed MPD makes total sense since it simply proposes no more than the SOP’s for these engines stipulated in the relevant OEM AP’s. I’m not saying it is right or wrong, but those are the facts from the MPD draft. Also of note is that no one has panicked, but simply stated quite correctly that IF the proposed draft MPD is rubber stamped as is for engines past 20 years since overhaul (and they are out there), it WILL create a great deal of casualties, that much is certain.
We both know that a great many of these engines in flying airframes have not been and don’t go through the anti det’s and inhibiting according to the letter of the book since last overhaul or retirement. I have witnessed this at several organisations. I’m not suggesting that such airframes are not maintained correctly by the way, just realistically stating that we know that airframes sometimes sit for months without engine FCU’s being re-inhibited with the relevant OM fluids, or anti det runs for various and more than often, valid reasons. Has every one of your Hunters and relevant engine types been anti det as per the Rolls book and similarly inhibited when it fell even slightly outside of the OEM schedules instructions in the AP during off season??? Obviously a rhetorical question which I don’t expect you to answer , but that is a relevant question based on exactly what the draft MPD proposes.
No doubt MRO’s in conjuction with the GA surveyors and industry will discuss options (And of course CAA surveyors are willing to listen to solutions). Unlike the great many misinformed, those of us with a brain know that the CAA are not mindless mallet wielding autobots, in fact most are aviation enthusiasts too, especially your local surveyors. However, their business is safety after all. Let’s hope a safe compromise can be found, since we know that hardly any of the engines in current flyers qualify if you subject them to exactly what the MPD proposes, especially back dating it to last overhaul or since retirement.
mjrAre there any operational Speys under CAA jurisdiction? In any case, I would assume that they would have OEM support as the AMX programme is still ongoing.
If the HHA Bucc ever takes to the skies again then yes, although one would assume it will operate under MAA permit, since they are only interetsed in MOD contract work, so will therefore be outside of CAA scope anyway
mjrEven that is no guarantee, time muddles my brain, but I remember the figure of about 20 years in the MVP bag and it would require overhauling before being returned to flight status…or the bag.
Rolls Royce still have the capability to overhaul the Viper for commercial operators BTW though that could depend on the version, IE the engine in early HS 125 ( I won’t say BAe )
http://www.rolls-royce.com/products-and-services/defence-aerospace/services/repair-and-overhaul.aspx
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Indeed, very true, hence parlty why CAA introduced calendar backstops
Good call, forgot about HS125 Viper.
Bruce is right IMHO, this will effectively end ex 75% of ex mil fast jets on the civi register within 24months, unless operated by multi millionaires only, OR someone such as retro track can get the approvals to overhaul the systems and manufacture the parts etc. A Griffon overhaul is 90-100k, so an Avon…. £200K?? unless you fancy sending your engines to Northen lights in Canada who rebuild flying Avons and Vipers instead!
mjrThe good news is that with the military still using the Avon and the possibly Viper they should be supported
..
Unfortunately not quite the case. Those being leased by the military, sit under MAA permits, but are maintained by a civi MRO, and are supported for this scenario only. What this CAA MPD covers is permit a/c operated under A8-20, E4/M5, which is 99% of the civi vintage market. Neither the Avon or Viper are supported for civi operations by Rolls Royce, unless some sort of tie up can be negotiated and set up going forward. Rolls pulled their support for these types under civi permits a long time ago. What remains out there in terms of parts and overhauling flying engines, is new old stock under the part M maintenance category with relevant approvals, which up to now has not had the above MPD from CAA. However, it has always been there in black and white in the engine manufacturer SOP manuals (standard operating procedures) and relevant air publications for type. If anyone tells you otherwise, they simply haven’t read the gen or are telling porkies. This MPD has been there in a different guise in the OEM manuals.
To put some perspective on this. As others have already stated, this was coming at some point anyway. The war birds have been doing this for years, and no doubt contributes to the massive sums of money to fly them.
The FCU’s and associated systems on these engines are being operated in many cases, way past their anticipated life span in terms of time, under “on condition” discretion under the hours reached or calendar back stop scheme. Trouble is, while these components are currently covered under that scheme, they are still degrading (as has been found in several cases) possibly due to OEM anti det and inhibition recommendations not necessarily being followed and age (see Tony t post above). So simply looking at the calendar back stop or hours reached for “time before overhaul” won’t do, many of these engines only do a dozen hours a year, and sit around for months on end static off season. Not a problem if you can prove that the engine has always been and is being subject to the manufacturer anti dets.
Leave your car parked in a cold garage for 4-5 months over the winter without running it, then use it, likely it will be fine, but you don’t see the cumulative damage from hygroscopic brake fluid, petrol in the injectors and fuel hoses becoming aireated, breaking down etc, attacking and degrading the system very very slowly, jet engines are no different.
These anti dets are what is being enforced under the MPD, but back dated to last overhaul too. We can’t really complain about it, since the directive simply requires that the engines have been maintained to the original OEM recommendations, which is what the part M approval already requires of an MRO anyway!!
IF, as an MRO you have not been following the manufacturer recommendation for anti det exercises, and/or standing engines, or there are gaps in the engine’s history, the engine is no longer airworthy under the manufacturers guidelines. IT could be worse, they could be saying, well if the fuel system on the engine is more than 10 years old, you cant fly it at all, regardless. Admittedly, proving that you have covered the engine since its last overhaul or back stop exactly according to the OEM anti det rules, will be challenging, as most will have gaps, unless they have sat in their bags inhibited since last overhaul, or have been ground run once a month. The second you drain the inhibiting oil from the fuel systems and fit the engine to an airframe, it is subject to the relevant anti det runs for its life, unless you re-inhibit it as per the book, overhaul it.
Fact of the matter is, the degraded diaphragms have been found, and the manufacturer has simply stated that to help stop it, follow our original operating procedures. It is harsh, but simply echoes what the manuals already state.
A significant game changer if the draft is approved.
mjrNo they don’t, the CAA have specified the engine types, probably as similar HP pumps and FCU systems are used on all of the engines specified. What is the important phrases IMHO are that the operators can prove that their engines and fitted components have been anti det run or inhibited correctly with records to prove as such since the retirement of the items from military service. If they cannot, the engine is not airworthy and is rejected from further use until it can be proven to be so with components that have known history and storage.
My take on it too.
if this MPD goes through as proposed with Rolls blessing, IMHO there will be a great number of casualties for these engine types, and thus aircraft. It clearly states that this is an interim proposal, there will likely be further actions as the investigation into other similar age gas turbines, progresses. While it is referring to a particular diaphragm as the catalyst in this case, it also refers to general rubbers in the fuel systems, so don’t be surprised if the Orpheus and Spey are added too. The FCU’s all work on the same servo regulated kinetic principals, and similar metering methods. Likely that in this case (for the Avon 122), AAIB found degraded engine driven double D pump diaphragms, common to the 100, 200, 300 Avon, and some of the other types here. Failure of DD pumps/seals generally leads to some rather undesirable behavior. I believe that the pumps and seals are not OEM supported for flying engines? SOP’s for Avons specify anti det exercises once per calendar month while inactive. Left longer and Rolls literature recommends re-inhibit of the FCU and engine fuel systems if not mistaken. Engines in storage subject to same inhibition rules. I would guess that a high % of the existing engines in flying permit jets won’t fulfill this criteria.
Of interest with Avon DD pumps at least, is the initial set up and equipment required after one has been replaced on an engine. I would hazard a guess that no one in the UK has the cell facilities or said Rolls test rig to do that particular set up!
Lets hope that a cost effective safe solution, and support within industry can be found .
mjrAbsolutely 100% hit the nail on the head!!! Having worked on Hunters, and this exact airframe, I agree entirely!!! The speculation and nonsense is just out of control. Some of the tabloids are just abhorrent in their articles and remarks.
As someone that is involved in the maintenance and operation of the Hawker Hunter the time has come for me to remark on the numerous comments from the media and tabloids. Ever since the accident i have been constantly pestered by the media and tabloids, even to the point that they have turned up at the security gate trying to get in. I will not talk to any of them because i feel that the families of all the victims should not see the tragedy time after time and also it is down to the relevant authorities (CAA, AIB) to make any remarks at this time. I do know that most of the pilots and engineers within the industry that have an ounce of compassion are also refusing to give any interviews and that is why they are getting so called experts that have little or no experience in displaying the Hunter.My own opinion is that a lot of these people are only giving interviews to get themselves some publicity and no other reason.
mjrOne thing that gets overlooked on loads of twin seats is the emergency No2 blow down bottles.IIRC, Disconnect the emergency undercarriage down handle behind the instrument panel. There are blow down nitrogen bottles behind the seats on the cockpit rear bulkhead. They are often still charged. If you disconnect the u/c emergency down handle, the bottles wont be be set off by accident.
mjrTwo peneths worth;
from memory the only time we have ever had stripped gears on “J”, it has been down to water ingress seizing up the bearing in the gear shaft, or once, the priming solenoid valve sticking closed. We have never had gear failure for any other reason as far as I know. Are the numbers correct? You have 5-6 separate parts in the priming system.
Are you cross referencing these parts to the Topic 10’s before fit? The topic 10’s will give you all compatible combinations. IIRC the pressure in the priming line is pretty high. It’s been several years since I dealt with them, but I seem to remember that the priming bulb lights up at about 50psi. If your pressure switches for instance are for a different fit and don’t light until say 100 psi, that may be enough to strip the fibre gears? It’s worth taking the section ref and part number from each component on your s/b side, checking that against your topic 10 and doing the same for the port priming circuit. Check the priming solenoids for proper opening too (they get ignored on the outboards since they are a hassle to get at) for the outer engines, the ones under the inboard nacelle covers, pain to take off! (I assume its the same on the Mk2?)
At least once, we had to give one of them a thwack, sticking!
What type of Avgas are you using? Just a thought and very long shot, but if its de-fuelled stuff, could be contaminated? Have you had different sources for each tank? Might be worth getting a clean sample from the bottom of each tank drain, each side, spectro tested if all else fails. Probably wouldn’t matter with steel, or Bronze but fibre may well react to something after a few weeks imersed, like a stray few gallons of skydrol finding its way in for instance! amazing what you sometimes find mixed up in de-fuel barrells!
mjrIts a good idea Rich, but you really need to do some calculations or experiments on the bench with new gear and old gear, do some simulations, see what happens, because there are always Avgas fumes floating about in that vicinity, and if you overload the pump field coils and burn up the armature, you could well end up with a motor case containment failure and a flash fire. By all means do it, but reduce the fuse capacity to remove the risk of current over draw.
mjrtake them out, that’s what we do, it takes 2 guys 20 minutes to remove them, and about the same to put them back in. As a note the pumps can be found on RR Vipers and Derwents too. They are pretty plentiful. The motors don’t go bang though, because the gear is sacrificed instead. It’s the gearboxes that are like hens teeth
mjr[QUOTE= We’ve also sent one pump away for use as a pattern to have some new gears made that are slightly harder wearing than the original fibre items. [/QUOTE]
Rich I would be very cautious indeed with such a local mod. The Paxolin gear will have been specified to that particular shear loading to make sure that it DOES strip when the gearing stiffens up. This was a potential problem even in service for many 50-60’s aircraft, hence why a sacrificial gear was introduced. Pumps and cocks on the jets, use a calculated shear pin loading for the transfer gear instead, for exactly the same reason. This is done to stop excessive current draw, which would allow the motor to repeatedly overheat, and the armature/ field coils burn up starting a fire if it gets outside the motor casing!
It is Avgas after all, and it will go up instantly. Remember the motor is drawing something like 8-12 Amps initial (on a free serviceable gearbox), dropping to about 3-4 Amps continuous. The wiring, field coils, Armature and contactors are not designed or specified to experience excessive high load for more than 5-10 seconds. if you are going to put in a stronger gear, do the load calculations and then drop the circuit fuse rating down by the same % that you have increased the load capacity on the gear
The inline priming line isolation valve should suffice really. Any mods you carry out, outside of the ministry specification or design standard will only cause you big stumbling blocks down the line with your certification process. if you are going to do them now, try and do them once, using released Mods.
mjrseems to be mixed info on that, but the hey day was in the late 20’s and 30s. much of the latter war instrumentation is supposed to be “Radium free”. In reality I reckon that instruments were stock piled right up until late thirties, and fitted through out the early war years. It wasn’t just aircraft instruments either. quite often the give away is a dirty brown appearance of the lettering and numbers, although that isn’t always the case
mjrJust to add guys, Im no sort of radiation expert, I just took an interest in it some years ago when all this “hot instrument” debarcle cropped up through teh BAPC. there was an awful lot of scaremogering and missinformation about, so I did my own research. Theres plenty of info out there, just read through it. No on is saying that these instruments will kill you, but they have the POTENTIAL to be very dangerous becasue of their ages, not only intrerms of their condition, but the decay chain of the particualr Radium isotope used.
My understanding is that, 224, 226 and 228 were used in dial faces. 228 was apparently cheaper to get, hence used more often, also since it’s produced in the decay of Thorium 232, (and Thorium was used a lot in engine casings for strength), so R228 was more plentiful as a result. I dont know if its possible to know which Radium isotope you have in an instrument, but 228 had a very short 6 year half life, so far more active and dangerous, emitting much more energy as Beta particles, which penetrate deeper into tissue and bone than Alpha does. The Radon 222 gas it produces also has a much smaller half life of 50 odd seconds (as opposed to 4 days for R226 Radon gas which you would have time to unrinate out of your body before it continued along its decay path into nasties like Polonium!!), hence radon gas produced from the R228 isotope doesnt necessarily have enough time to pass out of your body before it decays back into a solid
ie Breath in 228 particles, some of which will be decaying inside you producing Radon222 gas, which then doesn’t have time to exit the body in fluids,(within 50 seconds) stays put as a solid and continues along its nasty little decay chain inside you, damaging cells as it goes. So, the point is, IF you breath in particles from a surface contaminated instrument face, the damage is done much later! Once, twice, you will get away with it, open up or mess with 4-5 instruments, or do it fairly regularly……well you get the picture….
just don’t be flippant around these old instruments thats all. Personally I dont touch them with a barge pole
mjrduplicate post
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