Today's Message Index:
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1. 05:14 PM - Re: Re: Commander 520 from 1953 questions. (Jack B. Mills)
2. 05:42 PM - Re: Re: Commander 520 from 1953 questions. (Chris)
3. 07:15 PM - Re: Re: Commander 520 from 1953 questions. (Tylor Hall)
Message 1
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| Subject: | Re: Commander 520 from 1953 questions. |
Hi Adam,
I also owned a 337C for quite some time and put over 1,000 hours on it.
That birds problem is, of course, the Continental IO 360 engines which are
very prone to case cracking. Having said that, the Skymaster was really
CHEAP to operate as compared to my Commander. They are both great
airplanes, but are completely different birds.
Regards,
Moe
N680RR
680Fp
--------------------------------------------------
From: "stratobee" <adam@adamfrisch.com>
Sent: Saturday, January 01, 2011 11:05 PM
Subject: Commander-List: Re: Commander 520 from 1953 questions.
>
> I appreciate the candor.
>
> I came very close to owning a Cessna 337 some time ago and have been at
> the Skymaster forum for many years, so I think I have fairly good idea of
> the costs of twin ownership. This being 15-20 years older and bigger and
> with unsupported engines, will probably add a bit to that. I'm expecting
> to see about $30.000/year, all in. Hopefully less than that, but that's
> what I've been told to prepare myself mentally for.
>
> The props are on the recurring 500hrs/5years AD inspection and have run
> 161hrs and 18 months since the last one. Annual was done this summer.
> Aircraft has 5500hrs total, which seems like a nice number for her age and
> hopefully means she's been flown and not been sitting idle too much.
> Engines are 850 and 900hrs respectively. Hopefully with a little babying
> they'll make it past TBO. I like to throttle back and look at the scenery,
> so hopefully I can run them at non-geared rpm's, 2500-2700rpm. I'm hoping
> they will take kindly to this. The $ 40K/engine quote I got from Central
> Cylinders in Omaha is going to be a tough pill to swallow when it
> happens...
>
> I'm planning for liability insurance only, no hull.
>
> Couple of questions:
>
> 1. The wing AD is not in effect on the first Commanders, right? I seem to
> remember reading that they only came with the models that mixed stainless
> steel with aluminum in the spar - was it somewhere around the early 60's?
>
> 2. What about the fuel cells - can they be repaired if they're damaged?
>
> 3. Heard that the engine mounts are a weak spot on these. Are they made of
> steel and can be welded/repaired? Is it a costly thing?
>
> 4. Are there any alternatives to the prop in case they need replacing?
> Someone mentioned something about a Queen Air prop STC?
>
> 5. Are there alternative (read cheaper) ways/places of overhauling the
> GO-435's than the quoted 40K?
>
> Any other weak spots on these early models I should keep an eye out for?
>
> Thanks,
> A.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=325277#325277
>
>
>
Message 2
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| Subject: | Re: Commander 520 from 1953 questions. |
stratobee wrote:
> Couple of questions:
>
I haven't seen anyone posting answers, so I'll try to help out with a
couple of these...
> 1. The wing AD is not in effect on the first Commanders, right?
The "big" AD (dissimilar metal corrosion) does not apply to the 520.
There are several other wing related ADs which do, however. The lower
spar cap radius where the spar exits the fuselage requires repetitive
inspections for cracks (and a modification if not already done). There
is also one requiring some reinforcements in the wing which involve
cutting a big hole in the leading edge. I don't remember for certain
when it has to be done, but 7000 hours sticks in my mind.
> 2. What about the fuel cells - can they be repaired if they're damaged?
>
Yes. There are multiple sources for new and re-manufactured fuel cells.
> 3. Heard that the engine mounts are a weak spot on these. Are they made of steel
and can be welded/repaired? Is it a costly thing?
>
The mounts are fabricated from aluminum and likely have already had
repairs made with over 5000 hours on the airframe. New or serviceable
mounts would likely be impossible to come by but they can be well
repaired by a competent fabricator.
> 4. Are there any alternatives to the prop in case they need replacing? Someone
mentioned something about a Queen Air prop STC?
>
Unfortunately no (unless something new has happened). The Queen Air
props are not approved for the GO435 installation. You're going to need
to continue the re-occuring inspection until they fail then either find
some acceptable used parts or bite the bullet and purchase new MV series
props which eliminate the AD.
> 5. Are there alternative (read cheaper) ways/places of overhauling the GO-435's
than the quoted 40K?
>
Very few shops will touch the geared lycomings these days. The gearbox
parts are getting very rare and expensive. I purchased a set of new
cylinders about 12 years ago and was told at the time that they were the
last NEW jugs in existence although there must be a few around
somewhere. An item of note: a shop is required to have a repair station
license and approval to overhaul the geared lycoming engines. That's
one of the reasons so few shops work on them. Not worth the hassle.
You might find someplace that will overhaul them for less money, but
remember two things: there is a big difference between a "service
limits" overhaul and a "new limits" overhaul. Also, at overhaul, you're
getting "less worn out" parts rather than new for many items.
> Any other weak spots on these early models I should keep an eye out for?
>
Overall, it's a great airframe with few major problem areas. The
biggest trouble spot that I've seen is the truss assemblies in the
nacelles. These trusses are fabricated from 7075T651 aluminum (modern
designation) and are subject to inter-granular corrosion. They attach
to the wing spar and are the primary attach points for both the landing
gear and the engine mount. Inspect very carefully where the ears
protrude through the firewall and become the engine mount attach
points. This area is usually hidden behind some baffling material and
almost always has corrosion. Also, there is a side-ways brace running
diagonally outwards from the outboard truss. It should be removed from
the airplane and the area where it attaches to the lower spar cap inspected.
Commanders tend to have greater levels of corrosion throughout the
airframe. I believe this is because many of them have spent their lives
non-hangared. It's not really due to any aspect of the design other
than it's size.
I'd also verify that the engines have the larger 1/2" exhaust valves.
The earlier p/n 7/16th valves are very prone to breaking and causing
expensive damage.
The old Goodyear brakes are no longer supported. They were pretty good
brakes and easy to work on, but the silly pucks have become quite
expensive. Stock up on spare parts when you run across them.
Oh, and just purchase a 55gal barrel of 5606 and the proper tools to
make your own hydraulic hoses and you'll be a happy camper.
Hope this helps a little.
Chris
Message 3
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| Subject: | Re: Commander 520 from 1953 questions. |
Chris,
I have made hydraulic hoses before. We had it part of my shop.
Can a owner make Aviation Hydraulic Hoses for his own plane?
Hose and fitting are easy. Parker has aviation hose and fittings.
What about paper work and record keeping????
Tylor Hall
On Jan 2, 2011, at 6:39 PM, Chris wrote:
>
> stratobee wrote:
>> Couple of questions:
>>
> I haven't seen anyone posting answers, so I'll try to help out with a couple
of these...
>
>> 1. The wing AD is not in effect on the first Commanders, right?
> The "big" AD (dissimilar metal corrosion) does not apply to the 520. There are
several other wing related ADs which do, however. The lower spar cap radius
where the spar exits the fuselage requires repetitive inspections for cracks
(and a modification if not already done). There is also one requiring some reinforcements
in the wing which involve cutting a big hole in the leading edge.
I don't remember for certain when it has to be done, but 7000 hours sticks
in my mind.
>> 2. What about the fuel cells - can they be repaired if they're damaged?
>>
> Yes. There are multiple sources for new and re-manufactured fuel cells.
>
>> 3. Heard that the engine mounts are a weak spot on these. Are they made of steel
and can be welded/repaired? Is it a costly thing?
>>
> The mounts are fabricated from aluminum and likely have already had repairs made
with over 5000 hours on the airframe. New or serviceable mounts would likely
be impossible to come by but they can be well repaired by a competent fabricator.
>> 4. Are there any alternatives to the prop in case they need replacing? Someone
mentioned something about a Queen Air prop STC?
>>
> Unfortunately no (unless something new has happened). The Queen Air props are
not approved for the GO435 installation. You're going to need to continue the
re-occuring inspection until they fail then either find some acceptable used
parts or bite the bullet and purchase new MV series props which eliminate the
AD.
>
>> 5. Are there alternative (read cheaper) ways/places of overhauling the GO-435's
than the quoted 40K?
>>
> Very few shops will touch the geared lycomings these days. The gearbox parts
are getting very rare and expensive. I purchased a set of new cylinders about
12 years ago and was told at the time that they were the last NEW jugs in existence
although there must be a few around somewhere. An item of note: a shop
is required to have a repair station license and approval to overhaul the geared
lycoming engines. That's one of the reasons so few shops work on them.
Not worth the hassle. You might find someplace that will overhaul them for less
money, but remember two things: there is a big difference between a "service
limits" overhaul and a "new limits" overhaul. Also, at overhaul, you're getting
"less worn out" parts rather than new for many items.
>> Any other weak spots on these early models I should keep an eye out for?
>>
> Overall, it's a great airframe with few major problem areas. The biggest trouble
spot that I've seen is the truss assemblies in the nacelles. These trusses
are fabricated from 7075T651 aluminum (modern designation) and are subject
to inter-granular corrosion. They attach to the wing spar and are the primary
attach points for both the landing gear and the engine mount. Inspect very carefully
where the ears protrude through the firewall and become the engine mount
attach points. This area is usually hidden behind some baffling material
and almost always has corrosion. Also, there is a side-ways brace running diagonally
outwards from the outboard truss. It should be removed from the airplane
and the area where it attaches to the lower spar cap inspected.
>
> Commanders tend to have greater levels of corrosion throughout the airframe.
I believe this is because many of them have spent their lives non-hangared.
It's not really due to any aspect of the design other than it's size.
>
> I'd also verify that the engines have the larger 1/2" exhaust valves. The earlier
p/n 7/16th valves are very prone to breaking and causing expensive damage.
>
> The old Goodyear brakes are no longer supported. They were pretty good brakes
and easy to work on, but the silly pucks have become quite expensive. Stock
up on spare parts when you run across them.
>
> Oh, and just purchase a 55gal barrel of 5606 and the proper tools to make your
own hydraulic hoses and you'll be a happy camper.
>
> Hope this helps a little.
> Chris
>
>
>
>
>
>
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