IO-470VO cracked case

k9medic

k9medic

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Sep 27, 2018
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N Central FL and GTC Bahamas when off work
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ATP-H, CMEL, CSEL, CFI/CFII Airplanes and Helicopters
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At an LZ near you
I was chasing a pesky oil leak for a bit on my 310Q. After finding and replacing some old oil cooler gaskets, there was an dramatic decrease in oil seepage. During the annual, we came up with a plan to eventually replace the pushrod seals to clean up the bottom of the engine as well. Last week we had a break in our schedules and tackled the project.

It took about 2 hours to drop the exhaust, the intake and to replace the seals on #'s 2,4 and 6. Those were the worse offenders.

After starting and doing a leak check, we noticed that the #2 pushrod seal was still leaking. Suspecting that it may just need to be reseated, we were able to finess the intake section out and pull the pushrod. That's when we found it... A lovely crack from the bottom stud of the cylinder, all the way through the pushrod hole.

For the life of us, neither saw this crack the first time when the pushrod was put back in but it is sure there now.

Both engines are at TBO with the last overhaul back in 1998. This plane flies about 50 hours annually now. New engines are stupid priced so there would be little to no value in buying a new one so I am entertaining some options and open to suggestions -

1. Complete overhaul - $45-50K
2. IRAN and repair/replace the case - $15-20K
3. Find a mid time (900-1000 hr) engine - $20-25K
4. Sell the plane as is for abour $50,000

FWIW, it's a 1973 310Q with autopilot and 430W. Nothing too fancy but a good plane all around.

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I think the first question is whether this is an airplane you want to keep and feed for the next 10 years? If so, I'd go for a rebuild. If not, I'd chart the most economical path towards selling it, even if that means investing money in it up front.
 
I'm partners in a 421C as well that we just put new engines on to the tune of $220K!

I will need a plane for the next 12 years at a minimum. It doesn't really matter what plane I have though. The value on 310Q's has been a little flat but selling is an option.
 
I would do the overhaul. If you sell the plane, the engine times will be a big part of the math on what someone will pay for it. You won’t get 100% of the overhaul cost back, but probably enough to be happy with the $30,000 difference between IRAN on an over-TBO engine and 0 SMOH.

Said as someone daydreaming about upgrading from a 310 to a 421 and making big spreadsheets to figure out how much seed money I should put into the engine reserve fund based on engine times.
 
yeah buddy, welcome to my life in 2023. I went with option 4. I wouldn't incur the price risk just to sell, I lost very little by selling as is. Yes, reduces your market pool since only folks with the ability to cart the airplane off the property will bid, but even then I had no shortage of offers, of course I priced very "competitively". :biggrin:

I never found option #3 to be a real world actionable available option; this hobby is an insufferable scavenger hunt as it is, forget with the limitations of fac built. Most quotes/providers straight up refused #2 or quoted de facto option #1 numbers in order to insist I went that route. Even then the lead times and general lack of interest in my business, is what finally drove me to #4.

Even though it has been a hellish 2 years driving a commute I could have easily flown (granted I didn't have it when the airplane broke, my username checks... always), I don't regret the decision to part with an airplane that was never going to be a forever plane. I say it now I say it again, powerplants are the achilles heel of this hobby, and what will eventually sink it, not avionics upgrade affordability as commonly lamented.

You got access and are already price-sunk into another airplane for more than I spent in housing. This is an easy #4 choice from where I sit as a member of the has-been club.
 
hindsight2020 said:
….powerplants are the achilles heel of this hobby, and what will eventually sink it…
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Yep. Now, if Rotax would give aviation a 240hp engine like the did the SxS market, I could see a twin with that setup being worthwhile, even though twins have been pretty much replaced by the SETP.
 
Option 2. Cylinders look good just re ring them. Make a good multi time builder.
 
what engine is in the 310?
There is a SB/AD(?) for some large bore continentals in which a crack in a Non-Critical area can be scribed, monitored.
(although allowed, understandably some would not take that course of action)
 
ETA: option #2 is underquoted as a hypothetical anyways, so I reject the legitimacy of the option on that basis alone.
 
3, then 4 for the combined amounts. Time is of the essence, the piston twin market is starting to de-froth itself.
 
schmookeeg said:
3, then 4 for the combined amounts. Time is of the essence, the piston twin market is starting to de-froth itself.
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The piston twin market exists in 25-hour increments for now. It’s one rule change from effective extinction.
 
schmookeeg said:
Ah gotcha. That's what killed every arrow and cutlass when they allowed TAA in lieu of complex for CPL yeah? :)
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Yep. When I went thru the E-3 schoolhouse 25 years ago, all the initial quals were done in the sim. We’ve all had the discussion about transferability of piston twin skills to twin jets. It’s only a matter of time.
 
I'm not sure many are lining up to rent a middleweight twin like a 310 for their ATP, but.. I've seen sillier things. RIP those owners, doubly if they're leasebacks.

I'd be real worried if I was a school and just bought a new Seminole. :D
 
I wouldn't worry about it. We got a guy at our airport that can fix that in a jiffy with a bit of JB Weld and a coat of paint ... :rofl:
 
TCABM said:
Since 25 of the 50 hours for a ATP can be done in a full flight simulator, only 25 need be done in an airplane.
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My understanding today is 50 hours multi ATP won't get you hired. Hence multi time building.
Same thing with 1000 hour ATP-R won't work today for most. I hear it's brutal out there.
 
bonefishpete said:
My understanding today is 50 hours multi ATP won't get you hired. Hence multi time building.
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Don’t confuse hiring mins with regulatory mins. ATP can just as easily sell you hours in a full flight simulator without the liability of a piston twin and they can probably do it cheaper/more profitably that way, too.
 
Yup, and when the US airline market cracks the ab initio, sim/mpl code in the US, the recreational spam can is cooked. Even the military has lost its mind and started sunsetting primary military training for very shortened piston basic and sims.

Sell mortimer, sell! :biggrin:
 
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hindsight2020 said:
ETA: option #2 is underquoted as a hypothetical anyways, so I reject the legitimacy of the option on that basis alone.
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DivCo case is $1800 with a good core. Without a core, I am at $8000.00 The plane was just in annual about 4 months ago and has 10 hours since. The crank is an M10 crank so providing it is good, the cylinders could actually go back on. No need to do a top overhaul.

It would be a continued time motor but it would be sufficient to get it back in the air.

I have a contact out on a 500 hour 470 right now. Hoping to get this thing back in the air before the end of the year.
 
k9medic said:
DivCo case is $1800 with a good core. Without a core, I am at $8000.00 The plane was just in annual about 4 months ago and has 10 hours since. The crank is an M10 crank so providing it is good, the cylinders could actually go back on. No need to do a top overhaul.
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So while apart you wouldn't even mic the cylinders? Just remove and replace? Not even check the rocker arm upper bearings?
k9medic said:
It would be a continued time motor but it would be sufficient to get it back in the air.
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You have a A&P that's willing to sign his name to this?
k9medic said:
I have a contact out on a 500 hour 470 right now. Hoping to get this thing back in the air before the end of the year.
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iu
 
Doc Holliday said:
So while apart you wouldn't even mic the cylinders? Just remove and replace? Not even check the rocker arm upper bearings?


You have a A&P that's willing to sign his name to this?
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I'm not the one who will being doing the work. The shop would be.

It would be a normal assumption that it would be done IAW M-0 but then again this is POA and normal assumptions are not typical.
 
k9medic said:
I'm not the one who will being doing the work. The shop would be.
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Like I said, kinda amazing a shop would be willing to assume such a risk.
k9medic said:
It would be a normal assumption that it would be done IAW M-0 but then again this is POA and normal assumptions are not typical.
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This doesn't have to do with the MM, it has more to do with an aggressive attorney down the road, especially if you are renting this out to the public.
 
I’d do a service limits IRAN with a Divco case and be done.

Throw the old accessories back on it.
 
k9medic said:
I'm not the one who will being doing the work. The shop would be.

It would be a normal assumption that it would be done IAW M-0 but then again this is POA and normal assumptions are not typical.
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We decided to do factory new engines on our 310Q in Dec 2024. We love the plane and never looked back. It’s made a huge difference. 6 month wait and $130k for both engines. We saw the overhaul costs just increasing to $56k and then whatever delays or extra costs from whatever vendor put us back at the same cost as factory new. We saw friends go through the overhaul frustration post covid and wanted nothing to do with it.
 
I wound up buying a mid time engine from BAS that came with new cylinders from 2024.

This will at least get me going in the interim.

The shop doing the midtime engine install will eventually do a teardown of the cracked engine, and we will slowly build it back up as funds allow.
 
Can a crack like that be repaired, or is that case junk?
If it's junk I assume both halves are junk?

Or can two different halves be matched, to make a good case?
 
k9medic said:
The shop doing the midtime engine install will eventually do a teardown of the cracked engine, and we will slowly build it back up as funds allow.
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Since you are in the air with a mid time engine, why are you rebuilding your old cracked engine? Will that be cheaper than just buying an overhauled or a reman engine? How many years at your current rate will that mid time engine last before TBO?
 
JeffinNV said:
Can a crack like that be repaired, or is that case junk?
If it's junk I assume both halves are junk?

Or can two different halves be matched, to make a good case?
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Depends. Some case cracks can be repaired (welded), others (holes) not so much. Divco did ours on the previous engine.
 
I remain skeptical such "liquid" inventory of running bolt-on ready engines exists, especially in the TCDS-hamstrung fac-built sector. Certainly wasn't my experience when going through this same situation and looking for options to get me back in the air.

The price inelasticity of the overhaul market informs the lack of the so-called fly-ready donor market. If such inventory existed in earnest, the overhaul market would soften dramatically. So exceptions do in fact prove the rule.
 
JeffinNV said:
Or can two different halves be matched, to make a good case?
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No, 99.9% of the time as the cases are initially manufactured as a pair and not as separate halves.

hindsight2020 said:
I remain skeptical such "liquid" inventory of running bolt-on ready engines exists, especially in the TCDS-hamstrung fac-built sector.
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They exist just as aircraft that don't require prebuys exist. However, they typically are not advertised in the public domain and are bought/sold by word of mouth.
 
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