dennyjr

Good Morning Everyone!

While I was trainingon my GP PT-40 with my instructor on Tuesday I had my first crash. I was practicing my takeoffs and it was about the 8th one for the day. I was approaching takeoff speed and I think I used too much rudder to try and straighten the plane. As the plane turned I decided to get it off the ground before it rolled. As soon as I got off the ground my instructor took over since it was heading for the trees. He took it between the trees at about a 60Â* degree bank, then we lost sight of it. He started to run through the row of trees but we were plugged in on the buddy box. By the time he got unplugged the plane had gone down in the nearby swamp. I found the plane after about 5 minutes and retrieved it. The nose of the plane was stuck in the muck and water. I pulled it out and took it back to the field to inspect it.

The only damage on the exterior was a slightly bent nose gear, a slightly bent left main gear, and a puncture of the monokote on the right wing. I removed the wing and my instructor saw that my wire from the battery to the receiver was burnt through, and the servo tray had come loose. I loaded the plane up and went home to tear it all down to make sure there was nothing else broken.

I removed the engine since it was submerged in the water and inspected it. I removed the muffler and some water came out of the cylinder. I then removed the backplate and more water was there. I also removed the fuel tank and the receiver battery. The plastic around the battery was all cracked, and the yellow covering around each individual battery was cracked and the batteries appeared to be leaking from the tops like the pack had exploded. This was the only damage inside of the plane.

My questions are:

Since I need a new receiver battery I am thinking about replacing the NiCd battery with a NiMH. What are your thoughts?

What is the best way to remove the water from the engine and re-lube it before using it again? I have heard WD-40 is good for this but I am not sure. My engine is an OS .46LA.

What other things should I do before putting it in the air again?

Thanks for all of your help

Dennis

Flypaper 2

Dennis:
Best thing for the engine is to put it on a stand and get it running ASAP. The fuel and heat will drive the water out of it and relube the engine. I would run at least a half a tank of fuel through it. The heat will vaporize the water. Hope this helps.

Campy

My Feedback: (1)

DO NOT START OR TURN OVER THE ENGINE !!!

COMPLETELY DISASSEMBLE IT AND CLEAN IT FIRST.

If you have dirt or grit inside the engine it WILL score the crank and/or cylinder liner.

You will need to pull the head and cylinder liner to get the con rod off the crank. Put an alignment mark on the top of the cylinder AND the block BEFORE removing it, also mark the con rod so you know which way it goes. The thrust washer (the part the back of the prop sits against) is a press fit and either has a Woodruf Key (half circle piece of metal that fits into a groove in the crank) or the crank/thrust washer has a groove. You will probably need a small gear puller to get this off. Then put the prop nut on the end of the crank to protect the threads and LIGHTLY tap it with a hammer to get the crank out.

Once everything is disassembled, wash everything INCLUDING THE CARB (don't forget to remove the high speed needle valve during cleaning), in some fresh fuel. When reassembling the engine use some light machine oil (3 in 1 oil or after run oil) on the crank, con rod bushing and cylinder wall. Then go run it on a test stand.

The NiMH battery is OK. I would suggest getting a larger capacity battery (1000 mah or larger) while you are at it.

If the receiver got wet, dry it out completely before using it OR send it back to the manufacturer and have them check it out (USUALLY a small/nominal cost).

Make sure you range check it WITH THE ENGINE RUNNING before flying it again. The vibration from the engine will many times show up problems not otherwise apparent in the receiver/servos.

I would also COMPLETELY AND THOROUGHLY check the whole plane over for damage. If it hit hard enough to damage the battery, chances are there is other damage that may not be readily noticeable. In particular, check the horizontal and vertical stabs to make sure there are no cracks. Also make sure the firewall and motor mount is still secure and the fuel tank does not have any cracks/splits in it.

CrashBurn69

My Feedback: (1)

I dont think the impact is what hurt the battery, but it sounds like it shorted out and caused a rupture. LISTEN to Campy on tearing down your engine. That one is a must. Wash it in fuel and then soak it in WD 40 or after run oil and then reasemble. Also check your fire wall good and make sure it did not get pushed in any. Make sure you disasemble the fuel tank and wash it good with fuel. Since water was ran through the engine, some probably went through the pressure tap back into the tank.

kdheath

If the engine is really grungy, get a cheap WalMart crock pot and put the disassembled engine in the pot in 50-50 auto anti-freeze and cook it 24 hours on low. Wash it out with plenty of hot soap and water, dry for a few minutes in a warm oven or use a heat gun. Be sure your gaskets and O-rings don't need replacing. Reassemble with ATF for lube and run it again and readjust everything. This is kind of the state-of-the-art in restoring goopy engines. Plus a great way to restore that $10 deal from the swap meet.

mscic-RCU

My Feedback: (6)

If you change to a NiMH battery pack, you will have to get a new charger also.

Campy

My Feedback: (1)

Not necessarily. MOST of the chargers out there today will charge both NiCD and NiMH. If he goes to a larger capacity battery he may want a different charger due to the chargine times involved.

MinnFlyer

My Feedback: (4)

If the engine was just wet, I'd go with Flypaper's advice and just run it ASAP.

But if it's gritty water, best to tear it down and give it a good cleaning first.

Mike in DC

If you have the skills, Campy's advice is good, but most likely you can get by with a lot less. I would take off the muffler, the back plate and the carb, and just flush the engine as much as possible with fuel. All three come off very easily, and provide plenty of access to places dirt might collect.