Common maintenance concerns for M20C

[Kesk]

Anyone have experience as an owner or mechanic with M20Cs? It's a 1966 one, Mooneys are one of the few models I have no experience on. Wondering if anyone could point out parts that often need replacement or things to watch out for.

[Bob E]

I've owned my '65 M20C for 36 (!) years now.  Someone asked a similar question last August; here's my response:  

https://mooneyspace.com/messenger/43859/?tab=comments#comment-161512

Edited January 9, 2024 by Bob E

[Kesk]

1 minute ago, Bob E said:

I've owned my '65 M20C for 36 (!) years now.  Someone asked a similar question last August; here's my response:  

https://mooneyspace.com/messenger/43859/?tab=comments#comment-161512

Link doesn't work for me, how have you liked it overall? There's only so much you can learn through manuals.

For instance worst job on a 172 is probably flap tracks, other than that not too much crazy I've ever had to do on one. I know Mooneys are a bit of a different ballgame.

[Bob E]

I love it!

Ok, I'll go ahead and just recopy my earlier comments here:

--------------------

As the owner of a ’65 C for 35+ years now (third engine, fourth interior, lots of aviation upgrades) I can give you some quick info:

·         Mooneys tend to be forever planes. Once you buy one, you want to keep it; people sell them mostly to get bigger and faster planes if their family grows and they have the money.

·         Probably the most cost-effective aircraft there is in terms of dollars per knot of airspeed.  At 10,000 feet I burn about 8.5 gph at 130 knots.  (180 hp carbureted)

·         Incredibly stable airframe.  Excellent crosswind landing capability.

·         The carbureted version seems to be far less susceptible to carb icing than other airframes. Not sure why that is.

·         The Johnson-bar version is way better than electric gear:  bulletproof, REALLY easy to use once you get the rhythm right, virtually zero maintenance, higher useful load.

·         Far more cost-effective than a Cirrus, and much more forgiving.  Lots of low-time pilots are buying the farm in their expensive Cirruses.

·         Noisy - -noise canceling headsets are a must, and make distance flying really pleasant.

·         ALWAYS keep a small vice-grip in the seat pocket.  When you least expect it, the pin holding the inner door latch to the shaft will break, trapping you inside.  It’s happened to me three times in 35 years.

THINGS TO PAY ATTENTION TO

·         If the nosewheel shakes on landing, it needs a new bushing that makes it like new again and will last for another few decades.  Lasar has the part. 

·         Don’t let the landing gear donuts lose tolerance; if they do they provide less cushioning and landings will stress the gas tank seals and other parts. My gas tanks have never leaked because I make sure the donuts are in good shape.)

·        Invest in bent-stem (metal stem) tubes.  Standard tubes have a straight rubber stem that is blocked by the hubcap and as a result is always bent, putting a strain on it.  Sooner or later it will give out and you have a flat main tire, usually on landing. Happened to me twice.  See attached photos

·         The fuel selector-gascolator needs to be cleaned every few years. That’s a special Mooney part and is hard to replace, so keep it maintained.

·         Biggest minor annoyance:  The wooden seat rollers – they wear out and split. They are easy to replace with nylon rollers for literally $5 if that happens.  I posted how to do it on Mooneyspace.

·         If you take the seats out, it's inexpensive and pretty easy to upgrade them yourself with Airtex vinyl and to add headrests.  (Photo)

I got rid of the vacuum-powered PC system; I don’t need the step (I keep it retracted) or the wing leveler – the airframe is so stable I really don’t need it.

 

Edited January 9, 2024 by Bob E

[Utah20Gflyer]

Some things you want to look for

Fuel tanks leaks

landing gear donut age and condition 

camshaft corrosion (hard to check)

airframe corrosion

steering horn

Some of the common ADs

1. Landing gear 100 hour lube and tension check 76-21-01

2. Mag switch check 76-07-12

3. Yoke control shaft check 500 hours 77-17-04

4. 100 hour prop ECI if you have the older prop hub.  

5. Fuel cap O rings 85-24-05

 

[Kesk]

5 minutes ago, Bob E said:

I love it!

Ok, I'll go ahead and just recopy my earlier comments here:

--------------------

As the owner of a ’65 C for 35+ years now (third engine, fourth interior, lots of aviation upgrades) I can give you some quick info:

·         Mooneys tend to be forever planes. Once you buy one, you want to keep it; people sell them mostly to get bigger and faster planes if their family grows and they have the money.

·         Probably the most cost-effective aircraft there is in terms of dollars per knot of airspeed.  At 10,000 feet I burn about 8.5 gph at 130 knots.  (180 hp carbureted)

·         Incredibly stable airframe.  Excellent crosswind landing capability.

·         The carbureted version seems to be far less susceptible to carb icing than other airframes. Not sure why that is.

·         The Johnson-bar version is way better than electric gear:  bulletproof, REALLY easy to use once you get the rhythm right, virtually zero maintenance, higher useful load.

·         Far more cost-effective than a Cirrus, and much more forgiving.  Lots of low-time pilots are buying the farm in their expensive Cirruses.

·         Noisy - -noise canceling headsets are a must, and make distance flying really pleasant.

·         ALWAYS keep a small vice-grip in the seat pocket.  When you least expect it, the pin holding the inner door latch to the shaft will break, trapping you inside.  It’s happened to me three times in 35 years.

THINGS TO PAY ATTENTION TO

·         If the nosewheel shakes on landing, it needs a new bushing that makes it like new again and will last for another few decades.  Lasar has the part. 

·         Don’t let the landing gear donuts lose tolerance; if they do they provide less cushioning and landings will stress the gas tank seals and other parts. My gas tanks have never leaked because I make sure the donuts are in good shape.)

·        Invest in bent-stem (metal stem) tubes.  Standard tubes have a straight rubber stem at is blocked by the hubcap and as a result is always bent, putting a strain on it.  Sooner or later it will give out and you have a flat main tire, usually on landing. Happened to me twice.  See attached photos

·         The fuel selector-gascolator needs to be cleaned every few years. That’s a special Mooney part and is hard to replace, so keep it maintained.

·         Biggest minor annoyance:  The wooden seat rollers – they wear out and split. They are easy to replace with nylon rollers for literally $5 if that happens.  I posted how to do it on Mooneyspace.

·         If you take the seats out, it's inexpensive and pretty easy to upgrade them yourself with Airtex vinyl and to add headrests.  (Photo)

I got rid of the vacuum-powered PC system; I don’t need the step (I keep it retracted) or the wing leveler – the airframe is so stable I really don’t need it.

 

Thanks, will definitely check out the gear condition. I kind of assume nosewheel shimmy on all these old planes because lazy mechanics don't like fixing them or don't know how. 

[hammdo]

I own a 66 and it will depend on what has already been updated. I have ~7500 hours on mine and a lot has been done to it. I know that may not seem helpful but it will depend on current condition the plane is in.

Fuel tanks, landing gear biscuits,  control yokes are some that come to mind - prop,- depends on if you have one that needs the eddy inspection @ 100 hours or not - corrosion is a big one…

-Don

[Hank]

Check for SB-208, corrosion in the steel frame below the windows.

Also check for spar corrosion under the back seat.

You'll find a C to be incredibly useful, versatile and fun!

[Kesk]

Thanks for all the replies. Obviously going to do a full AD compliance, SB-208 sounds pretty similar to the Piper spar inspection. I expect to have to do some gear work by the sounds of it.

[Fritz1]

I have owned a 68 G-model which is a C with a fuselage stretch in the late 90s, hydraulic flaps, electric landing gear, overall very reliable and self sufficient airplane, biggest items were tank strip reseal and landing gear actuator, smoked the existing one with the emergency extension crank and replaced with 201 mod kit that had an emergency extension pull cable, with all the speed mods cruise went from 137 kt to 155 kt on the same carb Lycoming four banger burning about 10 gph, biggest items to look for in a pre buy is spar corrosion and corrosion on roll cage tubes under side windows

[AndreiC]

6 hours ago, Fritz1 said:

155 kt on the same carb Lycoming four banger burning about 10 gph?

Wow, what speed mods do you have? I don't see 155 kts on my 200hp short body (E-model)! I want in!

[Fritz1]

Long time ago, all available mods besides a Lopresti cowl which was developed later

[Nokomis449]

I believe his numbers.  My G with several speed mods added prior to my ownership (I’ve only added the brake reversal STC) regularly gets 148-150 kts at 10.5gph loaded to near gross and I don’t have the one piece belly or 201 windscreen, which are arguably the biggest speed mods.  See the AV30 in the pic.  Plugging the raw numbers into the Avidyne yields the same result, so I think it’s solid numbers.  Pics are from different flights; the Avidyne pic was in a 40kt crosswind at 9k and still got me 147kts true.

And they call the G “the slowest Mooney”!