C421 experience?

RyanB

RyanB

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I have been reading up a little bit on the Cessna 421. Just wondering if we have any pilots on here that have experience flying it. I have read that it can't go more than 3 or so trips without maintenance and the GTSIO-520's are tricky engines. What the reason behind this?
Thanks!
 
Ryanb said:
I have been reading up a little bit on the Cessna 421. Just wondering if we have any pilots on here that have experience flying it. I have read that it can't go more than 3 or so trips without maintenance and the GTSIO-520's are tricky engines. What the reason behind this?
Thanks!
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Most of the maintenance on a 421 I have done has been electrical related. The GTSIO-52 are not particularly tricky. Keep a load on your props and don't let them chatter the gears or drive the engines. Also get a really good dynamic balance. The way I was taught was LOP and do power reductions with RPM reductions first. For cruise, let it turn RPM.
 
Geared engines... #1 reason I have a 185 and not a Helio
 
Henning said:
Most of the maintenance on a 421 I have done has been electrical related. The GTSIO-52 are not particularly tricky. Keep a load on your props and don't let them chatter the gears or drive the engines. Also get a really good dynamic balance. The way I was taught was LOP and do power reductions with RPM reductions first.
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That, and do your power reductions starting early and using small increments. Use of the speed brakes (if you have them) for stepdowns on the nonprecision portions of approaches (e.g., FAF-MAP on a VOR approach, or initial/intermediate segments of any approach) also helps.

But recognize that those engines are very complex and being pushed to their limits, so you're not going to get the same sort of longevity and low levels of maintenance with them that you get with a 180HP Lycoming O-360. Same for the airframe -- the pressurization cycles are hard on lots of parts of it, and it's really just an upgrade of the original non-pressurized 400-series cabin class Cessna twins, not designed from the git-go as a pressurized hull. So things will wear out sooner (and more expensively) than they will on a Cessna 172.

That said, it's a really nice airplane.
 
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They are only pushed to their limits if you chose to push them to their limits.
 
Henning said:
They are only pushed to their limits if you chose to push them to their limits.
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You mean, say, by operating them according to their handbook? Getting 375HP out of a 520 cubic inch aircraft engine whose basic design was intended for 260-285HP really is pushing the limits. That's why engines like this and the TIO-541 in the Beech Duke have comparatively short recommended TBO's and the experience is that they don't do well in making those without major work in the middle. The thing speaks for itself in that regard.
 
There's a 421 on the ramp in Port Aransas that you could probably buy for scrap value.

It landed here during the Great Recession after losing an engine overhead. The guy parked it, probably called the bank and said "Your 421 is in Port A" -- and was never heard from again.

It looked really nice. Now, after four years in the salt air...not so much.
 
Ron Levy said:
You mean, say, by operating them according to their handbook? Getting 375HP out of a 520 cubic inch aircraft engine whose basic design was intended for 260-285HP really is pushing the limits. That's why engines like this and the TIO-541 in the Beech Duke have comparatively short recommended TBO's and the experience is that they don't do well in making those without major work in the middle. The thing speaks for itself in that regard.
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Yep, if you run the numbers the marketing department wrote for a 421, it will be an expensive experience. Pull back the fuel and slow it down and it gets a lot less expensive.

The 285hp version is doing it at less RPM so is actually operating with a higher ICP, that is what gives the G- engine the advantage if you use it.
 
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Would you say this is a twin to stay away from? The baron 58 seems to be an all around performer, IMO one the best twins there is.
 
Ryanb said:
Would you say this is a twin to stay away from? The baron 58 seems to be an all around performer, IMO one the best twins there is.
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They are completely different airplanes. Unless you are talking a P-58 there is no pressurization (the P-58 isn't cheap to maintain and has a 10,000 hr life limit.) The 421 isn't a plane I would avoid. It would be my primary choice for a non turbine family plane.
 
Ryanb said:
Would you say this is a twin to stay away from?
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Not if it's what you need.

The baron 58 seems to be an all around performer, IMO one the best twins there is.
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It is, but I agree with Henning as to comparing it to a 58 Baron -- you can't compare a 600HP nonturbocharged unpressurized 6-seat cockpit-design twin with a turbocharged, pressurized 750HP 8-seat cabin class twin. It would be like comparing a 172 with a 36 Bonanza. If you need the 421, a BE58 won't do. If a BE58 will do, then you don't need the expense of a 421 and you'll probably regret having that much airplane to deal with all the time -- much as I came to regret having the Cougar most of the time, and traded back down to a Tiger, a decision I only rarely regret.
 
Ryanb said:
Would you say this is a twin to stay away from? The baron 58 seems to be an all around performer, IMO one the best twins there is.
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No don't stay away from it just know what your getting into. It has some unique characteristics regarding engine operations (as others have mentioned), so as long as you manage the engines probably it's not bad at all. I've seen other 400 series cessnas spend a similar amount of time in maintenance. Make sure you use the airbrakes (instead of prop braking) and gently move your power levers.

As far as handling characteristics it's actually a very nice plane to fly.
 
Like Cap'nRon said, reduce power early. Our Company Ops Specs require that we start about 5 minutes before descending by reducing the manifold pressure 3 inches, then three minutes later we do 1 inch per minute. Heavy handed pilots will crack cylinders. We also work power in for take off, that is about half throttle until the engines catch up, then not fast but not slow to full power. It takes a little practice to do it the way we want it done. The VLO for the gear is 175 KIAS so the gear can be used to help slow down.

The plane is quiet inside for a piston twin. We fly 421C models with the 90 inch prop turning at 1800 rpm in cruise. It is quiet enough for the med crew to have normal conversation with the patient. Although we do require the med crew to use headset during the flight.

Our useful load is 1400 lbs. This includes 600 pounds of fuel figured into the W&B as we keep 50 gallons per side in fuel and we have medical equipment on board.

As Henning said there are some electrical problems at times. Mostly because the switches are on a flat panel on the left side, and sometimes rain will leak through the window frame, down the wall and into the electric switches. Last month I had a main switch just quit in flight, like someone turned it off. I played with the switch until I found a position where I had power, and then had to hold it in that position until we landed. Fortunately I was close to landing so it really was not a big deal.

The Continental engines, GTSIO520-L or N engines are all rated 375 horepower. This is the airplanes muscle. More horses pulls heavier wagonloads but you have to feed the horses. We keep cruise at around 65% getting about 20 GPH fuel burn per engine. We flight plan 25 GPH.

We typically fly in the upper teens with some longer trips up to flight level 220. I have been up to FL250 a couple times but it wasn't worth the extra time to get that high.

Our hourly cost is figured with $7.00 per gallon fuel, and that totals a flight hour cost of $374.75. This includes engine and prop reserve. This is on a 1600 hour TBO, which we typically get our engines up to TBO.

A C-414A would probably be a better personal plane.

The 421 would be a plane to stay away from if you don't fly much. Seems like ours will break when not getting used.

And with that said our company is planning to phase out the 421 and go to the Pilatus PC-12.
 
Yes, yes I have. Logged some XC dual right seat KFCM to AirVenture last year in a 421C RAM conversion. It was an awesome bird...

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$375/hr? In another thread folks were saying a Malibu costs more than that to operate!
 
Zeldman said:
The 421 would be a plane to stay away from if you don't fly much. Seems like ours will break when not getting used.
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I think you can say that about most planes.
 
At the shop I work at we maintain two 421C's. I don't recall us doing anymore maintance to these vs. the 310's or 340's. One of the 421's I am surprised of the amount of oil changes I do. The boss tells me to go change the oil and I thought I just did it, after reading the times they fly the crap out of it. In the last 6 months at least 3 oil changes, 1 vacuum pump, both main tires and I think 1 bulb.
 
Zeldman said:
The Continental engines, GTSIO520-L or N engines are all rated 375 horepower. This is the airplanes muscle. More horses pulls heavier wagonloads but you have to feed the horses. We keep cruise at around 65% getting about 20 GPH fuel burn per engine. We flight plan 25 GPH.

We typically fly in the upper teens with some longer trips up to flight level 220. I have been up to FL250 a couple times but it wasn't worth the extra time to get that high.

Our hourly cost is figured with $7.00 per gallon fuel, and that totals a flight hour cost of $374.75. This includes engine and prop reserve. This is on a 1600 hour TBO, which we typically get our engines up to TBO.
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$7.00 per gallon times 50 per hour is $350/hr. Is the $374.75 dry?
 
421s are $700ish/hr birds. The GTSIOs fail much more regularly than the straight TSIOs, and it seems there's always someone on the Twin Cessna board with cracked cases. Other quirks of the design like tendency to lose oil pump prime (which often leads to engine failures on takeoff) aren't good things.

I'd buy a 414 unless the 421's useful load was truly necessary for the mission. Just the TSIO instead of the geared unit will easily save $100/hr, and you'll feel that extra cost when you get told you have a cracked case, time for a $60k overhaul.

Oh wait! They're both cracked! $120k, please.
 
dans2992 said:
$375/hr? In another thread folks were saying a Malibu costs more than that to operate!
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Keep in mind, the airplane he is talking about is flying professionally (air ambulance), so it is getting flown a lot more than a typical personal GA airplane.

The more hours you fly, the lower the per hour cost.
 
If you take 40GPH X $6 X 10 hours a month and don't care what the answer is because it's a rounding error on your finances, then this is a good bird for you.
 
Alexb2000 said:
If you take 40GPH X $6 X 10 hours a month and don't care what the answer is because it's a rounding error on your finances, then this is a good bird for you.
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Yeah, but the $60k overhaul when your case cracks and your vibration damper quits gets to be less of a rounding error.
 
Zeldman said:
. Our Company Ops Specs require that we start about 5 minutes before descending by reducing the manifold pressure 3 inches, then three minutes later we do 1 inch per minute.
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I'm very familiar with OpSpecs (FAA), which OpSpec (number) are you referring too?
 
Ted DuPuis said:
Yeah, but the $60k overhaul when your case cracks and your vibration damper quits gets to be less of a rounding error.
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You know a lot more about these than I do. What scenario do these make sense over a small jet or TP? Look at an MU-2 or older TBM or CJ 1… I don't get it.
 
Alexb2000 said:
You know a lot more about these than I do. What scenario do these make sense over a small jet or TP? Look at an MU-2 or older TBM or CJ 1… I don't get it.
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421s aren't necessarily cheaper to buy vs an older turboprop/jet (although a TBM will be 7 figures easy), but fuel burn is much lower in most cases. This is especially true on short hops.

I think you'll still have a hard time convincing me a C90 is equal or cheaper to own vs a 421, but if you own a 421 during a very expensive time or need high dispatch reliability, it's different.

I'd think if a 414 won't do it, a King Air/MU2/Conquest/Cheyenne is a good next step. Lots of variables on which makes most sense. Also Commander 690, although I don't like flying them.
 
Alexb2000 said:
You know a lot more about these than I do. What scenario do these make sense over a small jet or TP? Look at an MU-2 or older TBM or CJ 1… I don't get it.
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MU-2 is the only one I can think of that you can get into at 421 prices. The late model 421Cs with trailing link gear fetch a pretty penny as the premium of the breed, but a 421B is a solid performer with good condition/equipment/times for <$250k.

Turbines also run higher maintenance number potential by an exponent or two, however this can be mitigated some with foresight and the salvage market. Sometimes good deals come around on a mid time engine, snatch one up when the opportunity presents itself and pickle it for storage. It's the one big risk mitigation on the big ticket item. Prepurchase of a replacement engine can save considerable money depending on the market conditions when you NEED the engine. A mid time engine can often be bought for a dime to quarter on the dollar of new/complete overhaul depending on the type of engine. There are a lot of TPE-331-10s out there on Jetstreams that are no longer in service., so buying a turbine that uses these engines is a hedge against shortage of replacement. Remember this as well, for Pt 91 users, it will be the rare person that will run out a turbine in their life.

As for a CJ or any pure turbojet/turbofan, that is a whole different orbit shell of cost.
 
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Ted DuPuis said:
421s aren't necessarily cheaper to buy vs an older turboprop/jet (although a TBM will be 7 figures easy), but fuel burn is much lower in most cases. This is especially true on short hops.

I think you'll still have a hard time convincing me a C90 is equal or cheaper to own vs a 421, but if you own a 421 during a very expensive time or need high dispatch reliability, it's different.

I'd think if a 414 won't do it, a King Air/MU2/Conquest/Cheyenne is a good next step. Lots of variables on which makes most sense. Also Commander 690, although I don't like flying them.
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I was just considering your earlier comment about 421 engine cost. Seems you could easily find a mid-time turbine for $70K if you needed one. Also, you could buy a runout turbine aircraft for part 91 use as Dave S. is doing and get in even cheaper.
 
Alexb2000 said:
I was just considering your earlier comment about 421 engine cost. Seems you could easily find a mid-time turbine for $70K if you needed one. Also, you could buy a runout turbine aircraft for part 91 use as Dave S. is doing and get in even cheaper.
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That mid time turbine cost is more than a factory new GTSIO-520.
 
The reason i ask about the experience with this aircraft is mostly regarding handling characteristics and the geared engines. As someone stated above the GTSIO's have more failures than standard TIO's. Was curious about the reliability of these engines. The 421 to me seems like its a high end twin! Would love to fly one sometime.
 
Alexb2000 said:
Top of the page has a $60K estimate for a cracked case. Like I said, I don't know, that's why I'm asking?
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Cracked case is the worst case scenario, and that indicates top price. Understood you are asking for information, just trying to provide it. The answer to why there is a market for the recips is cost differential, both perceived and real. A turboprop will most likely cost considerably more to operate than a 421. A turbojet/turbofan operates in an entirely different league of costs. I could afford to buy a Lear 24 cash, heck, I could buy a Mig 21 cash, however I could not afford to fly them.

BTW, I would bet the guys cracking the cases are pulling back the rpm in cruise a bunch and upping MP for efficiency. Best to let a GTSIO spin up and keep the torque and ICP down.
 
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There's a reason why a similar 414 fetches more than a 421. The only real difference between the two is the engines...
 
Ted DuPuis said:
There's a reason why a similar 414 fetches more than a 421. The only real difference between the two is the engines...
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That's the thing, a 414 runs with much higher ICP, that is the advantage the gears give you, you get to turn the engine in a more comfortable RPM range while keeping the prop tips in a low drag regime. What you have working against you is a bull gear set and the asymmetric case loads that provides.

What you have to do is operate in a way that makes best use of the positives while reducing the impact of the negatives. That means letting the engines spin up RPM even if it does cost you a bit of fuel efficiency, and slow down a bit by reducing the fuel flow to below "Marketing Cruise". This way you reduce the torque on the bull gear set and reduces the shock value of every power pulse into the case. The other advantage to keeping the engine spinning is you keep volume through the turbo while limiting heat buildup, important with pressurization.

In Long Beach we maintained 2 421s and 3-414s, and I watched the traffic at Tom's next door as well, and IME 414s get more engine and cylinder work than a 421. The way Chooch ran his GTSIOS he got 2000hrs out of them and we didn't do much in between replacements. The other guy with the 421 was a "I didn't buy this plane to go slow" guy, and he wasn't spending more than the 414 guys. BTW, talk about lost money, what about all those TSIOL-550 water cooled 414 conversions? Back in the day Tom's and everybody was cranking them out as fast as possible. Is there one left?
 
I flew for an operation that had two A's and a C. I enjoyed flying all of them, but I wasn't paying the bills. The ex-fighter-pilot chief pilot was all over treating the engines tenderly and had a set of engine operating parameters (some of which have been mentioned in this thread) that were inviolable.

My only shut-down-and-feather was in a 421 (can't remember which one) but the cause was loss of boost because of a turbo plumbing problem, so it's not a knock on the 421 itself...could have happened on any turbocharged engine.

On more than one occasion I had my wife along on deadhead IFR night flights over the mountains...that's an expression of faith in the machine.

Bob Gardner
 
It's not just the ICPs. Yes, methods count, but the engine's high RPMs aren't entirely helpful. The reason it has that convoluted vibration damper on the back end is because of the high RPMs. Lycoming had the same issue on the Duke and P-Navajo (2900+ crank RPM), but solved it with an extra set of counterweights on the crank, which was more reliable. Vibes in 421s are very bad.

A 350 HP TSIO-550 in a 414/421 would provide equal or better performance (less drag from the smaller cowls) and more reliability.
 
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