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231 annual questions


jrwilson

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Hi all,

Getting ready for the annual and the plane will be at 500 hours SMOH.  Going to put in a SureFly mag replacement and overhaul the other mag.  
 

looking through the service manual, looks like the vacuum pump and fuel selector valve need to be overhauled.  Anything else need overhauling at 500 hours?
 

is anything required for the alternator?    I also have a cycling noise in the radio along with the amp gauge fluctuating.  Wondering if something should be done with the alternator/regulator?

thanks in advance!

 

 

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You should replace the vacuum pump at around 500 hrs. whether it is running well or not. That is their lifespan, and when they fail it is generally a sudden failure. Don't want that in IMC, especially if you do not have a backup AI.

The mags need to be at least inspected every 500 even if not rebuilt or replaced.  If you run LOP as I do, the mags are the most common source of trouble running LOP in my experience.

The O2 bottle needs to be hydrostated or even replaced every few year, the period varies depending on the type of bottle.

I don't know what to tell you about the alternator. The coupler is a weak point in the design of the 231, but it is best left alone if it is working well rather than disassembling and trying to inspect, I think. When it starts to fail it will tell you, you will have intermittent charging.

I get the turbo inspected for leakage, and I have sometimes had my A & P borescope it. Its over a thousand hours but so far so good.

Have the hot prop checked if you have one.  You don't need it until you need it, and then you really need it. The contacts tend to wear out.

Those are the main things.  There are lots of other things that need checking, but they are on the 100 hr./annual checklist.

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At every annual have the exhaust tubes thoroughly inspected and joints lubricated with Mouse Milk.  The turbo has a  habit of quickly deteriorating the exhaust.  At 500 SMOH you should be fine assuming the exhaust was also overhauled at that time.

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That’s a good point. With a turbo you really can’t tolerate any nicks in the exhaust, the thing is cherry red in operation much of the time. There is a heat shield over the collector (the main exhaust tube that all the cylinder tubes feed in to). It is just a piece of sheet metal. It can droop or fold down over time and the edge can cut the collector. There probably is one on both sides.  Not a mechanic, just things I have seen.

Oh, and two other things. One, have them take the quick drain out and let the oil drain through the big hole. That let’s anything swimming in the oil drain out, small pieces can block the quick drain from sealing. Then have them check the quick drain and if necessary install a new “kit” to make the quick drain seal.  That applies to any engine, not just a turbo or the 231. 

The other is to make clear to the mechanic that you need 24 GPH at max power. Its actually 22.5-24, but they always set it low and you wind up with 21 or something like that. You need 24 to keep the engine cool during takeoff and a prolonged climb in the summer. You can always dial the fuel down but you can’t exceed the mechanic’s setting. If you have an intercooler, insist that they use the STC to set the fuel flow, not the standard SID. I guess its not called the SID any longer, but they will know what you are talking about.  Get the STC from Turboplus or whoever the manufacturer is, and give them that. I can practically guarantee they will set it too low anyway.

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17 hours ago, jlunseth said:

You should replace the vacuum pump at around 500 hrs. whether it is running well or not. That is their lifespan, and when they fail it is generally a sudden failure. Don't want that in IMC, especially if you do not have a backup AI.

The mags need to be at least inspected every 500 even if not rebuilt or replaced.  If you run LOP as I do, the mags are the most common source of trouble running LOP in my experience.

The O2 bottle needs to be hydrostated or even replaced every few year, the period varies depending on the type of bottle.

I don't know what to tell you about the alternator. The coupler is a weak point in the design of the 231, but it is best left alone if it is working well rather than disassembling and trying to inspect, I think. When it starts to fail it will tell you, you will have intermittent charging.

I get the turbo inspected for leakage, and I have sometimes had my A & P borescope it. Its over a thousand hours but so far so good.

Have the hot prop checked if you have one.  You don't need it until you need it, and then you really need it. The contacts tend to wear out.

Those are the main things.  There are lots of other things that need checking, but they are on the 100 hr./annual checklist.

 

13 hours ago, jlunseth said:

That’s a good point. With a turbo you really can’t tolerate any nicks in the exhaust, the thing is cherry red in operation much of the time. There is a heat shield over the collector (the main exhaust tube that all the cylinder tubes feed in to). It is just a piece of sheet metal. It can droop or fold down over time and the edge can cut the collector. There probably is one on both sides.  Not a mechanic, just things I have seen.

Oh, and two other things. One, have them take the quick drain out and let the oil drain through the big hole. That let’s anything swimming in the oil drain out, small pieces can block the quick drain from sealing. Then have them check the quick drain and if necessary install a new “kit” to make the quick drain seal.  That applies to any engine, not just a turbo or the 231. 

The other is to make clear to the mechanic that you need 24 GPH at max power. Its actually 22.5-24, but they always set it low and you wind up with 21 or something like that. You need 24 to keep the engine cool during takeoff and a prolonged climb in the summer. You can always dial the fuel down but you can’t exceed the mechanic’s setting. If you have an intercooler, insist that they use the STC to set the fuel flow, not the standard SID. I guess its not called the SID any longer, but they will know what you are talking about.  Get the STC from Turboplus or whoever the manufacturer is, and give them that. I can practically guarantee they will set it too low anyway.

Thanks for the info, all good advice!

I'm getting the vaccum replaced and one mag overhauled, the other changed for a Surefly.  The O2 bottle was replaced last year (Pricey!).  I do need to get the hot prop looked at...

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  • 1 month later...
3 hours ago, kortopates said:

Did the Surefly fit and get installed on your 231? How do you like it?

Surefly is installed.  Needed an oil hose reroute (new hose) but other than that if fit fine.  Starts faster and idles better.  No real performance gains because of fixed timing

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12 hours ago, jrwilson said:

Surefly is installed.  Needed an oil hose reroute (new hose) but other than that if fit fine.  Starts faster and idles better.  No real performance gains because of fixed timing

Was it one of the hoses to the wastgate by chance?  Its a very tight fit and the original hardware with split washer to hold the magneto on is too thick to fit under the Surefly case. I may be within a .001" clearance now with a star washer. 

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On 9/27/2020 at 10:24 AM, kortopates said:

Was it one of the hoses to the wastgate by chance?

I think he has the GB/LB, but I could be wrong. 

The return from the turbo could pose a problem with the left mag depending on how it is routed. 

Cheers,

Dan

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33 minutes ago, DanM20C said:

I think he has the GB/LB, but I could be wrong. 

The return from the turbo could pose a problem with the left mag depending on how it is routed. 

Cheers,

Dan

You're so right - no hydraulic wastegate. Now I am curious. Don't think the Surefly will fit in the Left position given how rotation is so limited between the alternator and vernatherm - maybe, but there is much more room on the right side where its just blocked by the alternator. Turbo hoses shouldn't be a factor on the right position.

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