Bulldog

[stevef]

The engine TBO is reduced to 1400 hours with the aerobatic inverted oil system. Something to bear in mind regarding operating costs.

[hugh flung_dung]

SteveF: where did you find "engine TBO is reduced to 1400 hours"? The AEIO-360 has a reduced TBO but (AFAIK) not the IO-360 fitted to most Bulldogs.

HFD

[stevef]

HFD - sorry, I couldn't remember the AEIO-360 designation at the time, that's why I wrote 'aerobatic inverted oil system'. As you say, the IO-360 has the standard TBO.

We have a Bulldog in our hangar at the moment and a very solid bit of kit it is, too!
Steve.

[TwoDeadDogs]

Hi all
What's so special about these replacement bolts? Is there no way that a standard MS or NAS bolt can be used? I've encountered this kind of thing on another aircraft and smelt a rat from the word go.I had no choice but to use the "special" bolts, which turned out to be metric bolts on an Imperial aircraft, at 50 quid a shot.There has to be a way around it.
regards
TDD

[A and C]

I don't have the full details but these are oversize close tollerance bolts that have to match the re-worked holes.

I am sure that the guys at DH support are smart enough to know the difference between a standard bolt and what is required for this job.

[Mandator]

SPECIAL BOLTS

TDD: The bolts are special because they are 64th inch oversize on the standard AGS diameters. This allows for reaming the exisiting bolt holes and hopefully taking out all the nasty little cracks which have already started to form by the time 114 FI is reached. The reaming also makes sure that the exisiting holes in the spar and the newly drilled holes in the reinforcing straps are in perfect alignment. Failure to use the right bolts and the right techniques will invalidate the subsequent fatigue testing which was carried out after the fatigue test specimen was repaired by embodiment of the modification; it will jeopardise the future ultimate life of 200 FI if the mod is not done correctly. The answer to getting the cost down is to run a programme of say ten aircraft at a time, which will make it economic to produce runs of reinforcement plates and fasteners. Also, the learning curve of doing what is a serious dockyard job can be spread over the whole batch of aircraft; the turnround time will also drop sharply as the team gains experience. This job is not one to be tackled by every M3 on a little airstrip doing just one aircraft.
To pick up an earlier post, there are no Bulldogs without a fatigue life limitation to when modification BH193 must be carried out. The ex-RAF ones still using a fatigue meter can run to 114 FI, which can exceed as much as 10,000 hours if the aircraft is flown carefully. However, all the rest (ie, those without a fatigue meter) are lifed very much on the safe side at 5,000 hours before the modification must be carried out. All Bulldogs - ex-RAF or not - then encounter a tailplane attachment limitation at 15,000 hours, but that is far enough down the pike not to be a concern at the moment. In answer to Meon Valley Flyer, the real problem with the spar is that during the full scale fatigue test it bust. Therefore, not doing modification BH193 is not an option for Bulldog owners if they want to fly (safely) beyound 5,000 hours (or 114 FI on an ex-RAF aircraft).

[TwoDeadDogs]

Hi there,
I'm not doubting you,but it smacks of the Chipmunk/Tiger Moth saga all over again.Aircraft that are sold to the public and suddenly require major mods to make them "safe", after years of rugged military service. Either they're fit for flight or they're not.The bolts I had to put in mine were also close tolerance oversize.
regards
TDD

[Mandator]

BUYER BEWARE

TDD - you could hardly expect the RAF to dispose of its Bulldog fleet with all of them freshly modified and ready for 50 years of effortless life in the hands of their new civilain owners, especially with the current Government holding the purse strings. Buy a Bulldog, either ex-RAF or ex any of the other military forces and you are buying military surplus kit - its the law of the jungle, buyer beware. Some of the RAF Bulldog disposals represented a really good buy, especially for the person who got the one aircraft which had Mod BH193 embodied. On the other hand, other Bulldogs were clapped out and in need of serious cash to be made fit for purpose. Most of these seemed to find their way to the States where they fly as Experimental and their owners ignore the fatigue lives - until the first one claps hands like the Beeches did, that is. The fatigue life issue was made quite clear at the time of the RAF disposals and to those who did their research it came as no sudden surprise that a big modification was in the offing. Indeed, when the first batch of aircraft was sold the ex-RAF Bulldog Series 120, Model 121 did not have any form of civil certification and it could not be flown on a CofA; that situation was sorted out quite quickly, but at great cost in time, effort and no doubt hassle for the people involved. In fact, British Aerospace went so far as publishing a letter which advised their forecast of costs to purchase and embody the fatigue modification. It seems to me that the bottom line is that if you want an aircraft which holds together with standard bolts, has a relatively long fatigue life and is cheap and easy to maintain then you have to buy what might be a rather bland US aircraft designed and built for the civil market - a characterful British aircraft designed to meet a military requirement, such as a Bulldog, or a Chippie or a Tiger for that matter, does not fit the bill.

[A and C]

Ann Robinson syndrome ?

First I would like to thank Mandator for puting flesh on the bones of what I had said, my reseach into this matter only went deep enough to decide that the Bulldog was not the aircraft for my business because of the spar issue costs.

What seems to be a very worrying train of thinking from some of the posts above is a hint that "someone is ripping the poor pilots off" and no doubt "they" whoever "they" are are getting rich and stoping the fun.

This is the type of thinking that I would expect from the likes of Ann Robinson and the rest of the BBC's Wachdog team.

I do think that the BAe price to fix the Bulldog spars was aimed at the MoD with a veiw to them not looking at it to hard at the price before saying "yes" to the work. I also think that the "real world" engineers in the GA industry can bring the price down BUT there is no getting around the techincal issue of the fatigue life of this wing structure.

This is not a "consumer issue" it is not an industry "rip off" it is about keeping the wings firmly attached to the aircraft and it is not going to be cheap, the RAF did the sums on this and that is why they replaced the aircraft.

[MEON VALLEY FLYER]

I second that thanks to mandator. That clearly says whats what. Like most I thought of a Bae rip of attempt. But you really need to look at it as 'military surplus'.
The bulldog was bought to do a job with a finite life span in mind, as with most military kit, and without any future value in mind at the end of this.
It was tested to ensure it was suitable for task and a weakness found. but this was within the scale of use and life the mod needed so nothing was done. If they wanted them to last longer SAL could have redesigned them and huge cost and removed the issue. It wasn't needed, so the fatigue issue is here now.

Sensible answer. buy them at the right price, enjoy them and all get together at the end and sort it our for less £.

[gyrotyro]

Bulldog fatigue index

Hi

The French seem to take a more pragmatic view.

There are some Bulldogs operating here in France and when operated on the "F" register they come under a permit to fly situation and the fatigue index does not matter.

[MEON VALLEY FLYER]

But surery whatever registration its on won't stop the wings folding !!!!!!!!!!!

[Mandator]

MVF - Got it one, good buddy! A crack in the main spar cannot tell the difference between the registration letters or whether the aircraft is on a CofA or a Permit.
The Yanks ignore the airframe lifing also, as they did on the Beech whatsits - until they clapped wingtips.

[TwoDeadDogs]

Hi all
I stand corrected....I thought the Beechs that crashed were all involved in regular aerobatics and mock dogfights and subject to greater stress than most of their breed.Also, the operators of those Beechs have come up with solutions to the spar problem (at least three available) without delay, gross expense and official handwringing.
regards
TDD

[Mandator]

TDD
There is no delay with the Bulldog answer - modification BH193 is ready to rock and roll right now. If you buy the bits and do the job on an individual aircraft basis then costs will be high. However, set up a programme and run say ten or twenty aircraft down the same line then costs will be contained. I don't think there is any official handwringing going on - you ignore the life limitations at your peril.