This month Mike, Paul, and Colleen talk fluids. Danny has an oil leak, Steve has a fuel leak, and Jeff is puzzled by guidance on which oil to use. Plus, a question from a maintenance newbie, looking ahead to overhaul, seeing double on batteries, and a pesky propeller governor problem. Submit your question to [email protected] for a chance to be on the show.

Full notes below:

Dash has a T-34 and is wondering about the implications of having two 12-volt batteries in series, rather than one 24-volt battery. Paul says one battery is simpler and less costly to maintain, but two 12-volt batteries in series can generally push out more current. You can treat them as one 24-volt batteries and use the applicable trickle charger, Mike says. To do this you would take a 24-volt charger and treat them like one battery, Colleen says. Take the cables and hook up the positive from one battery and the negative from the other battery. They all cautioned to make sure not to hook anything to the short, stout cable connecting the two batteries. Dash also says a mechanic at his airport told him not to continuously charge the battery because it will reduce capacity, but the hosts say that’s bad advice and that a trickle charger can be on the batteries all the time.

Danny has a continuously oily windshield on his Bonanza, which he thinks might be coming from the top of the case. The engine has 2,200 hours and looks great on the borescope, and he’s hoping an overhaul won't be necessary. Paul said he definitely wouldn’t pull an engine for this. He goes straight to the crankshaft seal as the offender. Mike thinks the o-ring that seals the prop to the flange is another good culprit to check. Mike said oil coming from the top of the case would go on the back baffles and other spots inside the baffles, not on the windshield.

Chris has an O-540 on a Cherokee 6, and although the engine is still running strong, he’s planning ahead and wondering if a rebuilt or overhauled engine is better. Mike said this is the worst time he’s ever seen to do anything to an engine. Colleen said she thinks people are risk averse and she’s always overhauled engines and has been very happy. Mike said the only reason to go rebuilt is if you know you have to replace a major component or if you want to minimize downtime.

Mahesh is looking for resources to become better acquainted with managing the maintenance on his Cirrus. The hosts recommend the Cirrus Owners and Pilots Association seminars, owner-assisted annuals, and Mike’s books https://www.amazon.com/dp/B08KHDPPWG?binding=kindle_edition&qid=1643661371&sr=8-4&ref=dbs_dp_rwt_sb_pc_tukn

Sebastien and Tim have a Murphy Super Rebel with a governor problem. The propeller wanders 35 rpm up and down, and they’re wondering if it’s a problem and how to fix it. Colleen suggests checking the integrity of the rod end to the bell crank.

Jeff has a Lancair and wants to switch oils, but Continental Service Information Letter 19-04 that says operators shouldn’t change oil until the engine is overhauled. The hosts all agree that this was a misguided document, and that switching oils will have no determinantal impact to the operation of the engine.

Steve’s Piper Lance is weeping fuel and he is wondering how critical the problem is. His A&P said he could take the tanks out to have them resealed, but all agree that this isn’t necessary. Paul said the Piper maintenance manual and FAA maintenance advisory circular have a good chart to show the various fuel leaks and what to do about them. If it’s not leaking bad enough to pull the tanks he said it’s probably not worth doing anything.