No your not Gary

I flew a Dutchess that had the same problem - and one 421 with the same problem. But my 421 is not like that at all. I have been told that wallowing struts are due to them being serviced with an improper ratio of hydraulic fluid/nitrogen.

Dan, how much difference does TL really make to your landings? Does it turn an "arrival" into a "greaser"? Are there any other benefits apart from smoother landings?

I can't see why the TLs command such a price premium.

IMO, it's the tyranny of small differences. It's a small, but readily noticeable difference, and there's some general consensus that the TL is better (if everything else, including price, was held equal).

Now, I think it is better but only by a small amount (again, everything else held equal). If that's the case, as a discriminating aircraft buyer with exquisite taste and the budget to operate a 421C, why would I even consider a 76-79 SL model?

Now, that we've established that, let the price vary.

Given that whatever market premium the TL airplanes command is likely to come back at sale time, you're only talking about a small capital cost difference, a small hull value insurance difference, and in some jurisdictions, a sales tax difference. All of those are small per $10K of purchase price, so our hero discriminating buyers will continue to pay a premium for the "better" airplane.

In my mind, the SL aircraft are better because they usually have a higher useful load. I can land an airplane well enough and my family isn't overly critical (and would be less so while climbing down an airstair), so for me, the cheaper, lighter SL is better.

The TL gear is stronger than the straight leg, taxi's very well (not like a Duchess) and yes it will make a bad or sloppy pilot look good.

Is maintenance much more on the TL compared to SL?

And I must say that I always assumed the SL would be stronger than the TL.

Maintenance is the same or less depending on the use. TL is 90 pounds heavier for a reason. It's much stronger and the TL gear was designed and used for the conquest I which has a much higher gross weight than the 421c.

There is an additional joint in TL gear that SL don't have. So there is some added costs in bushings and bearings that at some point have to be serviced/replaced.


It is 90 pounds heavier because the trailing link arm is all additional weight over a SL gear. The TL still needs an oleo strut, so the trailing link arm is all additional weight.

Being heavier and being stronger are not the same.

Also, the gear itself is stronger than the mounting points in the wing just due to the nature of having the strut and castings. So stronger gear does nothing for you in the end, the gear still rips out of the wing on a severe impact. I don't think I have ever seen a 400 series Cessna where the gear broke from weakness and the upper trunion was still attached to the wing.


It is not clear to me the parts are the same, and even if they were, the 425 GW is not overly more at 8600 lbs versus 7450 for the 421C.

I favor SL for the simpler, lighter system. I don't believe the TL gear any stronger.

Mike C.

There is an additional joint in TL gear that SL don't have. So there is some added costs in bushings and bearings that at some point have to be serviced/replaced.


It is 90 pounds heavier because the trailing link arm is all additional weight over a SL gear. The TL still needs an oleo strut, so the trailing link arm is all additional weight.

Being heavier and being stronger are not the same.

Also, the gear itself is stronger than the mounting points in the wing just due to the nature of having the strut and castings. So stronger gear does nothing for you in the end, the gear still rips out of the wing on a severe impact. I don't think I have ever seen a 400 series Cessna where the gear broke from weakness and the upper trunion was still attached to the wing.


It is not clear to me the parts are the same, and even if they were, the 425 GW is not overly more at 8600 lbs versus 7450 for the 421C.

I favor SL for the simpler, lighter system. I don't believe the TL gear any stronger.

Mike C.

Are the parts actually the same?


Based on what evidence?

It is heavier and it looks beefier, but TL requires more structure to achieve the same effective strength. You are putting a serious bending moment into the trailing link arm that the SL doesn't have, so that leads to heavier strong looking parts, but no actual real increase in effective strength.

Mike C.

If the SL gear is as strong as the TL gear why didn't Cessna just use the SL gear on the the Conquest I which has a 1,150 pound higher gross weight. Cessna would have saved a lot money in design and manufacturing .

Are the parts actually the same?


Based on what evidence?

It is heavier and it looks beefier, but TL requires more structure to achieve the same effective strength. You are putting a serious bending moment into the trailing link arm that the SL doesn't have, so that leads to heavier strong looking parts, but no actual real increase in effective strength.

Mike C.

Brad,
With TL, arrivals are comfortable and typical landings feel like greasers.

I purchased a TL for two reasons:

1. The wing spar issues and SIDs were a big concern when I was in the market from 2002-2004. These are my notes from then. I think the below info on SID compliance is still correct, but cannot vouch for that:
"421C serial 421C0001thru 421C0800 [straight leg]
Initial 5,000 hours
Initial after modification 12,500 or 13 years
Repeat 4,000 hours or 8 years

421C serial numbers 421C0801 thru 421C1807 [trailing link]
Initial 15,000 hours
Initial after modification 20,000 or 20 years
Repeat 5,000 hours or 10 years"
Although the SIDs are not mandatory in this country, there was concern that the SIDs would morph into ADs.

2. I knew that I would over-improve my airplane with excessive maintenance and upgrades, and excessive avionics. I knew that these expenditures would not be fully recouped on the eventual sale, but I figured that I would recoup on a higher percentage on a TL. TL buyers tend to be premium buyers, and are more apt to pay a higher premium for a premium TL. I expected that SL buyers would pay a smaller premium for a premium SL. In the big picture, this argument is relatively weak. Let's say that my plane is worth a $100k premium over the typical TL, but that if it were an SL, itwould be worth a $10k premium over the typical SL. That $90k premium difference is insignificant noise compared to 10 years of operating costs.

STRENGTH
I would rate the TL stronger in the sense that it absorbs bumps and accepts the shock of hard landings. The TL gear is weaker in that the arm of the tire from the vertical strut puts a large torque on the wing structure when there are side loads (see AD 91-25-08 R1). That is why after my greaser landing, I essentially come to a full stop on the runway before initiating the turn onto the taxiway (despite my plane having the beefup kits installed on both wings).

I would love to have another 100 ponds of useful load as my children grow heavier, but if I had it to do all over again, I would still buy a TL.

The 1980's and newer (serial # 801+) have the trailing link gear plus a slightly different spar. As I understand it, Cessna used a different metal in these spars and that's why the AD compliance times are different.

I don't recall the metal type, but I'm sure others will.

That all being said, I purchased a straight leg airplane. At least $100k less than a TL model plus more UL made it an easy choice for me. Both are obviously great airplanes though.

Robert

Marketing.

TL gear was the rage at that time.

Anything to sooth the pilot ego.

Cessna didn't switch to TL gear because the SL was too weak.

Mike C.