static leak

[skymaster]

just finished 73p annual. now going for static system chk. i am sure it had a leak. now starting to run it down. any suggestions. looking at the t connectors and diagrams it appears there is a connector in the wing root and another line terminating line in the mid cabin . could this be a misprint? we will start with the instruments last handled. ie. pressure differential, altitude alerter . absolute pressure tranducer. any guidance will be appreciated. J

[stackj]

Be sure to check your connections to the autopilot too.

[skymaster]

looking around all connections. we found the leak in the techs staic testing equipment. glad i was there so they could not sand bag me. J

[Bob Cook]

Deja vu

1) There is a connector at the pitot head which consists of rubber tubing and two clamps. This is a problem area and should look first if you have a PITOT LEAK.

Now for static. There are two static ports on the aircraft along with two bottles that collect moisture on each side of forward cabin. This can be a problem area. As far as leaks you start at the altimeter and work backwards. The autopilot, altimeter, blind encoder, etc. The only tube that runs back to the autopilot is routed along the pilot side of the A/C above the headliner.

Many times the tube running up the pilot side window post gets punctured with a screw. The original tubing becomes rather brittle and you may want to consider replacing the tubing with new.

There is no simple proceedure other than isolating the lines.

The Pitot goes thru the wing root. The static does not.

These suggestions cover both possibilities.

Bob

[skymaster]

i had been told the lines were surgical tubing. mine was clear tubing in good condition. the t connectors looked like something from the russian space program. lots of metal. glad to have this in the rear view mirror. Bob , thanks for your insight . its excellent. J

[Bob Cook]

Skymaster

The pitot does not make a real tight connection when the technician tries to seal the pitot with mastik as there can be leaks between the pitot head and the strut housing. In the first inspection cover between wing root and strut there should be a "T" connector fitting for testing of the pitot lines.

The fittings on the tubing should be plastic if I am not mistaken. I am surprised they are metal.

There is a piece of surgical tubing just behind the pitot head with two clamps up from a few inches of metal tubing. This was done to avoid overheating of the tubing I guess. In any event this is where you will most likely find a leak.

All my tubing is nylon.

Good Luck

bob