BeechTalk - BT

Username Protected · **Posted:** 30 Jul 2015, 19:02

Username Protected wrote:

So even if you do everything right when acquiring and operating one, you still have no idea if a previous owner of mechanic ran an engine at some point in time without oil pressure.

Note that this is true for any other airplane as well, to more or less extent depending on the design.

On the flip side, 421 GTSIO-520 seems to make TBO with more regularity than, say, the 340/414 TSIO-520.

Mike C.

Username Protected · **Posted:** 30 Jul 2015, 19:19

Username Protected wrote:

Robert

Who built your engines and when?

One is a factory reman, but was a factory new engine (case crack @ 1400 hours, decided to replace engine) and the other is a RAM engine.

I've had my host of issues, but loss of prime hasn't been one of them!

Robert

Username Protected · **Posted:** 30 Jul 2015, 19:26

The engines of this enquiry were overhauled ~2 years ago by Ram and have less than 200 hours.

Username Protected · **Posted:** 30 Jul 2015, 20:21

Username Protected wrote:

The engines of this enquiry were overhauled ~2 years ago by Ram and have less than 200 hours.

That's the time when mine was built by RAM and I had the problem until pump was replaced

Username Protected · **Posted:** 03 Aug 2015, 11:53

Username Protected wrote:

So even if you do everything right when acquiring and operating one, you still have no idea if a previous owner of mechanic ran an engine at some point in time without oil pressure.

Note that this is true for any other airplane as well, to more or less extent depending on the design.

On the flip side, 421 GTSIO-520 seems to make TBO with more regularity than, say, the 340/414 TSIO-520.

Mike C.

Username Protected · **Posted:** 03 Aug 2015, 11:58

Username Protected wrote:

The engines of this enquiry were overhauled ~2 years ago by Ram and have less than 200 hours.

That is a similar time frame to the engines that lost prime which I am familiar with.

Its not a risk of burning an engine if you pay attention on startup. It IS annoying if it happens to you and will cost you an oil pump.

My 421C with older RAM OHs never had the issue, and the logbooks indicated the engines always went beyond TBO with the past owner running 75% (225-230ktas).

Username Protected · **Posted:** 03 Aug 2015, 12:00

Username Protected wrote:

Man. So even if you do everything right when acquiring and operating one, you still have no idea if a previous owner of mechanic ran an engine at some point in time without oil pressure.

...and there goes the happy feelings about 421s beginning to fade.

You shouldn't get too emotional Don....you've actually got to buy one to get burned by it.

:duck:

(Just a light-hearted jab at a longtime tire-kicker)

:bud:

Username Protected · **Posted:** 03 Aug 2015, 14:58

Username Protected wrote:

Mike - this is an interesting statement. Do you have any data to back this up?

Not compiled and analyzed in a spreadsheet or anything, but looking at the engine times on the for sale listings, and discussing this with owners, it seems to be true, more so than TSIO-520N in the 340/414 from what I can see.

Quote:

The TSIO and GTSIO are the same engine except for the gearbox and the fact the engine works a lot harder in the geared version.

I don't think this is true despite the engine producing more power. Mechanically, the cylinders are different, as is the induction and exhaust systems, so the two engines are not the same parts.

The higher engine speed on the GTSIO reduces peak cylinder pressures (the cylinder spends less time near TDC with high pressure burning fuel in it). This reduces the stress on the cylinders, lowers CHT (heat transfer to the cylinder from the hot gas), and lessens burn off of the cylinder wall oil film. Further, and somewhat counter intuitive, the faster piston speed actually aids in reducing wear by keeping the cylinder walls more coated with oil and given the oil less time to squeeze out between parts. There was an article on this which I am unable to find presently showing a study done on car engines showing this.

Quote:

In my non-scientific experience, 421s with new cases make TBO if flown properly - the ones with reused cases are having issues and will typically develop cracks long before reaching TBO.

I wasn't aware that case cracking was so common in GTSIOs. I had thought it was more isolated than that. In any case, I don't see this issue reflected in the planes for sale, but perhaps it is being suppressed somehow.

I was "this close" to buying a 421 before I got the Jet-A disease, so I had researched this with some diligence. In the end, I am very happy I went turbine as I think I am flying my MU2 for about what a 421 would cost and goes so much faster as to be in a whole different league.

Mike C.

Username Protected · **Posted:** 03 Aug 2015, 15:24

End of story for now:

Ram replaced the oil pump with a new pump. They also stood up and absorbed much of the cost. Not a warranty replacement, but acceptable to the owners.

Username Protected · **Posted:** 03 Aug 2015, 16:07

Don,

Been flying 421s for years now and what you described is not uncommon. I have found the best practice is to fill the filter and the line at oil change then start the engines immediately after the change. Do not let it sit unprimed until your next flight or you will have a problem. Normally this takes care of it unless you have a leak somewhere. Personally, I have had good experience with the RAM engines but have to agree that they need to do something about the oil pump. Had the same experience even after having them install two brand new overhauls a few years ago.

BTW: I am looking :dancing:

for a super nice 421 right now, so if you hear of one please let me know. 500 AMU range. Looks like I missed out on Martti's plane.

Good luck to you and your friend,
Jim :cheers:

Username Protected · **Posted:** 03 Aug 2015, 17:45

Username Protected wrote:

Man. So even if you do everything right when acquiring and operating one, you still have no idea if a previous owner of mechanic ran an engine at some point in time without oil pressure.

...and there goes the happy feelings about 421s beginning to fade.

You shouldn't get too emotional Don....you've actually got to buy one to get burned by it.

:duck:

(Just a light-hearted jab at a longtime tire-kicker)

:bud:

Username Protected · **Posted:** 03 Aug 2015, 18:20

Username Protected wrote:

I've already gotten past the most important part, which is domestic CEO approval.

:dance:

I'm sure the fact that you can put everything in a 421 and use the potty has nothing to do with that approval, right?

Username Protected · **Posted:** 03 Aug 2015, 19:08

but the potty will probably never be used.

Username Protected · **Posted:** 03 Aug 2015, 19:41

Username Protected wrote:

I've already gotten past the most important part, which is domestic CEO approval.

:dance:

I'm sure the fact that you can put everything in a 421 and use the potty has nothing to do with that approval, right?

Username Protected · **Posted:** 03 Aug 2015, 21:43

Username Protected wrote:

I asked her if she wanted to go faster or go in more comfort with more room and a potty on board. The question was answered before I could even get the words out of my mouth.

So, buy an RV. Most room and comfort you can get in a moving vehicle.

Mike C.

Cessna 421 loss of oil pump prime.