Warbird Information Exchange

Any tips for keeping early Vampire pneumatic brakes serviceable?

Is low pressure a common problem with this brake system?

Are there any modifications recommended to make this system more suitable for operation at a busy airport (lots of stops during taxi)?

Start at one gear and then up the other and through the complete system replacing all the flexible lines. Use a bubble solution of a few drops of good liquid detergent and a drop or two of glyceryn to stream capable spray bottle. Then hit each and every fitting with the spray to check for leaks. Also make sure that the control valves are not bypassing and the pilot is not keeping a too much tension on the brake lever.

BTW...also use the correct torque values for all fittings. If they have been overtorqued....consider them junk for this purpose.

Where would you get new fittings- or would you have to replumb the whole thing with AN fittings?

Yes, as has been suggested, go through all the unions. It is difficult to overtorque the British fittings, but if they are having to be overtightened, it suggests a problem with the pipe.

Cracked flares are common, and will allow pressure to leak. Vampire has a lot of aluminium pipework, and this can lead to problems. Fittings are easy to obtain (www.lasaero.com; ask for a catalogue), but the flares are 60 degree, and very different to the American ones.

Common faults in a British air system:

1) Charging valve - though this has probbly been adapted for American use.
2) Pressure regulator - doesnt usually leak on the pressure side, but it can. Can be overhauled - let me know if you want a manual.
3) Air bottle - leaks around the end caps
4) Brake bags - if you leave the a/c with the brakes on, does the pressure drain away?
5) Other components - the canopy seal and canopy operating jack run off the same system. If they have problems, the pressure will drain away.
6) The brake valve can be troublesome, and the brake pressure instrument can leak as well.

A well maintained system wont drop any pressure at all.


Bruce

Thanks guys, I'll pass this info along. The brakes are the only remaining squawk.

BDK, If the air bags are like the Spifire system, don't engage parking brake if the drums are still hot from landing or taxi, the contact will melt a hole in the bag causing a major leak and the bag is too high pressure to be patched like an innner tube. Rather, use chocks. Another source of bag leaks at the air entry hose is if there is any play in the mounting plate.

_________________
Bill Greenwood
Spitfire N308WK