My pain is your gain.

I know that all Aerostars are different as mine is one of the 25 700P's with the intercoolers located behind the motor and ducted with a fiberglass duct so my situation may be a little different from the rest of the fleet. Most of you have not seen an Aerostar configured this way as it was the last year of production and sales were lousy. The more common location is below the motor.

Nevertheless, today we finally solved a pesky leak that has been plaguing my aircraft for over a year and has eluded two different A&P's and myself. We could never replicate this on the ground because it took airspeed to push the oil off where it collected. I am writing this to the group just in case you ever have a similar issue as this was a real mystery.

The leak presented itself as oil running along the bottom of the oil filter and then across some scat hose, along the pressure lines for the mags and then down the fuel servo and out of the aircraft. It was never a material leak but enough oil came out to make a cosmetic mess aft of the engine on every flight. Given where the leak could be seen (it was a line of oil running on the bottom of the filter) everyone insisted that it had to do with the filter or its mounting surface. Frankly, it looked that way to me.

We tried the usual tricks. We would clean it up, use developer, black light, etc. and run it up on the ramp for various times and never found the leak. At various times we thought that it was (a) a loose oil filter (b) a loose sending unit in the oil filter mounting bracket (c) a bad seal in the oil filter mounting bracket; (d) a leaking check valve in the turbo line; and (e) bad hoses. We did each of those things one at a time. As it turns out it was none of those.

The good news is that last week my vacuum pump suddenly quit and when we removed it there was clearly evidence of a leaky garlock seal although everything from the top of the pump (everywhere that you could see) was dry as a bone. Replaced the pump and removed the seal and it was obviously bad as it was barely making contact with the accessory shaft. The leak was completely solved.

The reason it was so elusive is that on my U2A motor there is a metal landing under the vacuum pump that provides a perfect path for the oil to travel over to the filter and stay there in a ground run up. With the tight packaging you really can't see this area with the pump in place and it takes a lot of oil to overflow the landing. FYI, my plane had the Tempest pump with the slot cut in the mounting pad which allows oil to exit out of the pump without entering the carbon section. It is not a bad idea but that groove is completely invisible once installed in this airplane.

Again, given the way my engine is situated there is no way to see the bottom of the mounting pad so that is why we never could get a visual on the source including with two mirrors. The leak was also elusive because the cooling shroud around the pump blows the air around the pump which evacuates the oil from the "landing". Although your engine may be different I believe that the location of the vacuum pump pad is pretty consistent across the Lycoming 540 motors.

In summary, if any of you ever have a leak coming from high on the back of the motor this is a good place to start.

Got plane back this afternoon.




Bit of a learning curve adjusting to the GTN650, the box is fine, the operator.... well, I won't be launching into IFR conditions for a few hours.


Thursday I'm either going to do a survey up the James River with a likely stop for lunch at Windwood (WV62), or I'll go out and do some instrument approaches, holds, etc and get comfortable with the new pilot interface.

Based on my short run from Hampton Roads to Norfolk, ADS-B traffic is much better than TIS traffic.

I'll post some pictures once I have time to take them.
(Visually the difference between a 7000B and a 350Hc; and between a GNS480 and a GTN650 isn't much), still, both have some color and that's pretty cool.

I'm figuring out trips that need to be done.

Forrest,

You might get kidnapped when i finally get to go inspect the perfect Aerostar

Anonymous work van and duct tape not needed, if it fits with my schedule, I'd be happy to tag along.

The Victor Airways is the best feature. Take a Garmin course or watch Youtube as there is a lot of functionality shortcuts buried in the unit.

Brad,

I hate to break the news to you, but you aren't going to buy an Aerostar or any other complex airplane. Your expectations of finding the "perfect" airplane are "visionary". At any given time in my ownership, there have been multiple gremlins, none affecting the safety or reliability of flight, just irritants. One of mine is sagging gear doors while parked. We've followed "standard procedure" and haven't fixed anything. The only issue untried is replacing a check valve on the hydraulic pump. Only, you have to buy the whole pump from A*, $5,000. Really?
Replace a perfectly operating pump so your gear doors don't sag?

Read Eric's post about chasing an oil leak and keeping two, that's TWO, turbos on the shelf.

My advice is keep the 350. You will be MUCH happier.

Jgreen

JG,

Call Jimmy M. PM if you need his number. He very likely has one on the salvage planes he has.

Forrest,

You mentioned A/C but forgot heat. I chased plenty of stupid gremlins on the heating system.

Tim

Tim,

I have already talked to Jimmy. So, it becomes a $2,000 fix plus labor/shipping/etc. to replace a perfectly good pump.

Nah, I'm beginning to like sagging gear doors.

Jgreen

John,

I understand and that is why perfect was in green an addition to half-way kidding about kidnapping Forrest for my test flights.

I consider myself fully warned as to cost/upkeep on an Aerostar

Always enjoy your post JG

My frequent trip is from Charlotte, NC to Monroe, La. Grenada is a whole 9 miles "out of my way"

When I find my perfect bird I would be honored to buy you lunch and take you up for a flight. Your explanation of gates makes a lot of sense to my small brain.

Heater is on my list.

Just before check autopilot.

Early in my ownership experience, my heater that would only act up when I was pressurized, froze my a$$ off more than once.

(Didn't check it on flight to pre-buy -it was a sunny day and Heat wasn't needed)

That was before I started going to Alan.

Steep learning curve at my local maintenance shop.

Memories.....

John,

It's too late for Brad.

Brad (and his wife) had the misfortune of coming up to Norfolk and taking a lunch trip up to Cambridge, MD with me.

He flew most of the trip up and back, there was a bit of weather which we climbed up through for a nice ride in the sunshine on top. We did a no drama rapid descent back into Norfolk (pressurized and high wing loading). It was the kind of short-ish trip the Aerostar is very good at.

He's seen the light.

Very true. I was delusional for a bit thinking a Meridian would fit my needs a little better. Also entertained idea of a 58P. One of the issues for me is lack of tolerance for pressure altitudes at/above 8,000. Flying an Aerostar with the 5.0 PSID I can fly FL220-230 and be below 7,000 cabin pressure.

Forrest,

That is just plane mean. Never take a pilot and spouse for a demo ride an Aerostar through rough weather. Not many planes have a higher wing loading, so it is super smooth, so the passenger will love it. And then the pilot gets to fly the plane....

Brad, I am sorry. But you are stuck, there is nothing that comes close to the A*.

Tim

It's an acquired taste. "Swing low, sweet chariots" comes to mind.

Over the years every airplane I have owned has taught me something, even if it was as simple as not to ever buy another one... But the A* probably tops the list of maintenance issues that were the most perplexing to track down. Not that the airplane has been overly problematic, it's just that some of the issues were quite unique compared to the normal things that tend to break on airplanes. Sometimes taking a couple years to ultimately figure out.

Probably the biggest head scratcher was a disappearing right brake everytime the cabin went positive for more than an hour or so. No leak to be found and the level in the reservoir would be higher upon landing. Pretty obvious air was getting into the system somewhere in the cabin, but where. The normal suspects, O-rings, seals, fittings, yielded nothing. Finally, the interim solution was to connect a tube from the brake reservoir to the cabin eliminating the pressure differential. Problem solved. At least for a couple years....

My plane still has 4-piston brakes, so when departing from my house in AZ with a 2200' runway stabilizing the power before launch requires a substantial amount of brake pedal pressure. I began to notice that while romping on the brakes the right one would begin to slowly bleed down. Still, no leak to be found. More O-rings, seals, etc... No joy. Finally, when standing on the brakes I began to notice a faint order of 5606 in the cabin; it's leaking somewhere... but still no drips. I removed the interior pieces to allow access to all the brake system and enlisted a helper to mash on the brakes while I closely inspected all the lines, fittings, etc. Right in the middle of the line that connects the pilot and co-pilot side master cylinders together and is mostly hidden from view by wiring, etc. in the center console I could see a pink haze. No liquid, just a pink cloud of atomized brake fluid. There was a minuscule hole in the aluminium line, so small that for years it would let air in, but not big enough to allow fluid to escape. A new line, removal the "reservoir pressurization kit", and the problem was solved.

Another leak that took a while to find was a persistent hydraulic mess dripping out of the belly and running back toward the tail. All the normal hunting and looking yielded nothing; clean the belly, swing the gear and so on, not ot a drop. Fly it for a while and there it was streaming up the aft fuselage and dripping on the floor. It had to be in the engine driven side of the system, but the frustrating part was you could run it as long as you wanted on the ground without losing a drop.

Now my idea of a good time doesn't include running the engine while the airplane is on jacks with the gear retracted, but that seemed a better option that tying someone to the outside to inspect for leaks while in flight... The leak turned out to be a pinhole in the hardline running thru the right wheel well. Behind the little identification label on the line, localized pitting corrosion I presume. I saw the same thing with the line from the pump on a Beech Sierra, a little bitty hole just like you drilled it underneath the ID label on the line with the remainder of the line was pristine.

Always something new to make me scratch my head!

Jeff