Piper Comanche PA-24 Service Manual page 425

7-21. Engine.
7-22. Removal Of Engine.
7-22a. Engine Mount Corrosion Inspection, Immersion in Water.
The following guidance is general in nature and should be applied or varied to fit the individual situation
based on water level during immersion, length of time immersed, length of time since exposure, etc.
Proceed as follows:
A. Inspection
1. Level the aircraft in accordance with paragraph 2-13 in this Service Manual.
2. In two of the larger, lower, engine mount tubes, drill a 3/16 inch hole in the bottom of each
tube, at th approximate mid-point.
3. Visually inspect the interior surface of each tube through the 3/16 inch hole for evidence of
internal corrosion. Pay particular attention to the lower end of each tube as this is where
corrosion is most likely to appear first.
4. Should evidence of corrosion be detected in step (3), above, replace the engine mount. If no
corrosion is detected, proceed with Corrosion Prevention, below.
B. Corrosion Prevention
If no evidence of corrosion is detected in step (3), above, proceed as follows:
1. Place a drip pan below the inspection holes in each engine mount tube.
2. Insert a plastic tube thru each inspection hole and feed it up to the high point of the engine
mount tube.
3. Using a syringe inserted into the end of the plastic tube, pump linseed oil into the upper end of
the engine mount tube while rotating the syringe / plastic tube assembly to assure maximum
coverage. Continue pumping until the lower end of the engine mount tube is filled with linseed
oil to the level of the inspection hole.
4. Now, draw the plastic tube out of the upper end of the engine mount tube and reinsert it in the
opposite direction, feeding it to the lower end of the engine mount tube.
5. Suck excess linseed oil out of the engine mount tube with the syringe / plastic tube assembly.
6. When linseed oil can no longer be picked up by the syringe / plastic tube assembly, remove it
and allow the engine mount tube to drain into drip pans for approximately two hours.
7. Purge excess oil from tubes by applying air pressure to each 3/16 inch inspection hole, one at a
time.
8. Insure that roughly the same amount of linseed oil that was pumped in is retrieved in the drip
pans.
9. Apply liberal coating of an approved fuel tank sealant (see Consumable Material, Section II) to
each inspection hole and seal the hole with an appropriate blind rivet. After installing the rivet,
apply a liberal coating of the approved fuel tank sealant over the head of the rivet.
04/01/09
PIPER COMANCHE SERVICE MANUAL
2A23
VII - POWER PLANT
(PA-24-180)