Sorry first chance I have had to get back to this thread, Training courses, even at my age someone believes I am still worth polishing up up a little.

The notes oddly enough were written up in 1974 while undertaking engineering training, prepping for a post as an instructor/fault investigator or as we called ourselves then, ‘Gremlin Hunters’, job was to track niggling faults on complex diesel/electric power plants which normal maintenance procedures had failed to rectify, interesting work.

Looking over MJR’s two peneths worth, sounds like the pumps are controlled by the pressure sensor, i.e. turned off when the set pressure is detected and a failure to sense this correctly may be the indication for the cause of the problem.

So from this brief information I would expect excess fuel to build up in the Carbs if the solenoid valves were not actually closing at some point indicating , either the pressure sensor is the wrong type, possible given time and chance etc, but not faulty as the valves are closing when a pressure is reached, fuel not pouring out of the carbs, second and more probable is that the link between the sensor and the operating relay for the pump has a problem, possibly in the protective coil supply for that relay, in short it,s not turning it off when it should causing the pump to over pressure.

All supposition based on very limited information really, but an interesting problem all the same.

Doubtful it’s a tolerance issue as the pumps are run for such a short period of time normally they would not really suffer unless they were almost seized to begin with.

As has been mentioned earlier in the thread, changing out components for ‘better’ materials could in this case lead to problems further down the line, brass would do the job but brings with it a number of problems based in the material itself, hence are normally reserved for low speed/low torque operations for this reason, I would look towards the Phenol based synthetic resin types for this application, all really depends on gear size/load/load type/pitch line velocity to name but a few items on a long list when choosing materials.

I would assume that the choice of fiber types was originally chosen for this reason as non metallic materials are often used in these applications, high pressure infused cotton moldings for one providing vibration dampening and high endurance against dynamic/static loads, they can even be made out of infused rawhide oddly enough but those do suffer from moisture ingress over time.

Will be interesting to hear what eventually turns out to be the problem.

Been really sad and pulled out my old note books from to long ago to remember and this is the description I penned all those years ago regarding fuel pump operations, (real ink)…

” Fuel drawn into the pump from source will initially be impelled forwards out of the pump until it reaches whatever impediment is installed to restrict it at which point it’s pressure quickly raises until the ‘set’ relief pressure is reached, the pump will continue to provide pressure from that point, flow circulating inside the pump housing through the pressure relief porting and at this point the pump will remain under it’s continuous ‘set’ load, .. below it’s actual maximum load, this condition will remain static until the restriction is removed at which point fuel pressure drops slightly, closing the relief valve causing fuel to flow from the pump body under pressure.”

As Richard pointed out both types of pump are positive displacement pumps and once they reach pressure they will stop rotating unless some method is in place to allow fuel flow to continue, if they are direct drive the motor will obviously stall at that point and probably blow any supply fuse or breaker, but if as shown a geared drive is employed the weakest point are those gears and my guess is that the fiber gears are employed as a safety device, stripping before any damage to the pump or motor occurs, so in essence, no matter how annoying they are working as designed.

In this case I would still look towards the pressure relief solution probably built into the pump body, these are normally set slightly above working pressure allowing fuel to continue to flow once pressure has been reached internally, this would simply be the bung up the hole method the solenoid valve’s provide to prevent over priming of the carb’s, Could either be a sprung device or less likely a restrictive static port arrangement machined into the case.

For those that might be interested Lancaster priming pumps are located in the inboard nacelle wheel wells on the rear of the fire wall, K40 or A.M. Type with either two separate cocks, one for each engine, Exception is the Series X aircraft which had a single priming pump which you turned the handle to left or right to supply the relevant engine on that wing, placing it central to turn it off once primed.

Talking about preserved GS littering the countryside brought back the memory of sitting astride a certain large bomb at RAF Scampton as a child on one of the regular visits we used to pay to the then gate guardian proper, years later turns out this particular example was reported to be actually ‘Live’ though there is some doubt about this, and had mistakenly been placed there were it remained for a number of years before someone realised there might actually be a problem with it.

Might be asking the obvious here, would a ‘Gas collator’ not be a better solution to this problem, although up rating the pump gearing might appear to be a simpler solution it does present problems with electrical changes to the system as pointed out earlier in this thread, the introduction of such a device would remove almost all water before it ever became a problem, allow pre flight draining of any collected water in the feed., just a thought.

True to form almost every airshow gets bad press because those going do not like the traffic, or the hawkers and the price of the snacks seems to hurt also, always makes me think back to Finningley airshow all those years ago, there was still horrendous traffic trying to get in and out, hawkers even then were in your face though I admit not quite as bad as these days, and the food/tea vans had there own special way of making 2/6 into a pound, never understood how they managed that but not to worry, we brought our own picnic, same as we do today and made it a family day out rather than a group of strangers choosing to go to the same place.

Lessons to be learned.

1, Traffic…..Sir you are the bloody traffic.
2, Hawkers.. Can be ignored.
3, Burgers….Don’t buy them, they always smell like wet nappies to me so I find that an easy rather than queasy one.
4, It’s a family day…..make sure you take advantage of that.

There is a lot of info available in Wiki along with a PDF scanned document from around 1956 covering the many variants of the in Military and civil variants along with specs and aircraft fitted with them.

Bubbles -you have got to admit that every few years in the Daily Mail the Trust use this one:

I totally agree with this sentiment and the ideal of retirement to Elvington.

There has been a lot of talk over the years regarding the funding and also the numbers of faces in the background of the organisation rumored to be snuffling in the trough and it is quite surprising how ready they are to call time on the project when it appears there income stream may be threatened with the old Chestnut ‘Cough up or the Vulcan gets it’ type of statement.

To point this out is only indicating nothing new on that front and also that the current CEO’s tenure has been divisive for many years and while not wishing to defend his position, which I believe for the most part these days is untenable, he is after all only a mouth piece for the trustees when issuing these types of threats even though in doing so he may secure a place at the trough for another few years.

It is interesting that the TVOC has now indicated that they intend to proceed with an attempt to continue flying the aircraft after this season, which indicates they have not only found a way to Mod the airframe and work around all the problems they indicated might ground it, but possibly to stretch the life of the engines for at least that period, how is yet to be revealed to those putting there hands in there pockets yet again.

As for the TVOC placing a block in the way of others obtaining finance, I doubt this is the case, they all have the same opportunity to raise finance in the market place and though pubic donations, that they might not be as successful in this is not the fault of the TVOC.

All depends on the size and depth of the hole you intend digging and the local conditions.

If you just require in wash prevention from back filling the excavation I have seen temporary barriers created from twin rows of of all things 1 tonne bags of sharp sand faced with plastic sheeting used in a river bed allowing work to be achieved inside this alongside a pump to remove seepage, cheap, rapidly installed and easily removed without environmental problems associated with metal piling or earth banking alternatives.
Again with little information on the site conditions and planned depth of excavation it would be hard to define a solution.