New AD (lwr strut/doorpost area) NOT Applicable to 170s.

How to keep the Cessna 170 flying and airworthy.

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GAHorn
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New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by GAHorn »

The new proposed AD note on lower doorposts/lower strut attach area of single engine Cessna airplanes does not apply to the Cessna 170 series.

It is the result of cracks found in several dozen 172N, 182E and later models as well as 206/207 aircraft. It will recommend a repetitive inspection of aircraft with more than 4K hours and a repair scheme if cracks are found.

https://www.gpo.gov/fdsys/pkg/FR-2018-0 ... -01923.pdf
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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mit
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by mit »

Comments open till March 19, 2018............
Tim
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BWeathered
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by BWeathered »

gahorn wrote:The new proposed AD note on lower doorposts/lower strut attach area of single engine Cessna airplanes does not apply to the Cessna 170 series.

It is the result of cracks found in several dozen 172N, 182E and later models as well as 206/207 aircraft. It will recommend a repetitive inspection of aircraft with more than 4K hours and a repair scheme if cracks are found.

https://www.gpo.gov/fdsys/pkg/FR-2018-0 ... -01923.pdf

I get that the AD did not list 170's but I wonder (quietly... sssh!) "Why not?' I understand that we are somewhat protected by smallish fleet size, which makes it more difficult administratively for the FAA to document a widespread problem worthy of an AD. However, is there something fundamentally different about our birds and the ones listed, or should we also be just a bit concerned even though we were not included in the AD?

Brent
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c170b53
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by c170b53 »

Humm...(again), not a bad question or bad idea to fully understand what the problem is. Model and serial number suggest it's models that have a lighter aft door post that are affected. Does the lighter aft door frame somehow have an effect on the the forward structure? I wouldn't think so but maybe the latter models also have a lighter front structure than our machines. I'm wondering about my XP, it's s/n 1723135, a 79 model which appears to have missed the calling but how is that possible? Unless of course someone has a problem with their keyboard
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
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GAHorn
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by GAHorn »

The gross wt of the aircraft would impact this, as would any change in sheet-metal ga., increase in wing-loading....(think fuel capacity/weight)... or operating speeds...(think "turbulence penetration"), etc. etc. The affected aircraft also have their gearboxes moved to the rear doorpost (they are all "tricycle-gear")... so the shock-wave at touchdown would be transmitted differently to the wing-structure/attach area, with the added phenomenom of "twist" applied as well considering the arm of that force.

The area in question is an area which should be regularly inspected in accordance with the 100-hr/annual inspections anyway. If cracks are found...they should be reported by the owner/operators.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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lowNslow
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by lowNslow »

Could also be that because the 170 has the gearbox structure almost right under that area making it less vulnerable. All the other aircraft in the AD have the gearbox further aft.
Karl
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bat443
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by bat443 »

different lower wing strut attach point on bulkhead, nose wheel airplanes included in the AD use a fitting to attach the strut to.
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wingnut
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by wingnut »

To illustrate the difference in the affected later model 172's vs. the earlier model 172's........
For the 172 series, the AD is effective beginning with serial number 17272885, which is the last year of the "N" model. Difference is obvious.
Cessna 172N pre-72885.PNG
Cessna 172N 72885 and after.PNG
Del Lehmann
Mena, Arkansas
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GAHorn
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by GAHorn »

lowNslow wrote:Could also be that because the 170 has the gearbox structure almost right under that area making it less vulnerable. All the other aircraft in the AD have the gearbox further aft.
That was the major point I was attempting to make when I wrote:
gahorn wrote:... The affected aircraft also have their gearboxes moved to the rear doorpost (they are all "tricycle-gear")... ....
Del's excellent post also demonstrates the structural differences between the early vs late serials of the affected models.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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c170b53
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by c170b53 »

Thks Del, hadn't seen the tech data on the proposal, looks my 172XP was old school, how fortunate, could it be worth more now? :D
Jim McIntosh..
1953 C170B S/N 25656
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hilltop170
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by hilltop170 »

Del's post says it all, thanks.

With similar door post/gear box sections as the C-170, but without struts, C-195s have cracks in the narrow section at the top of the front door posts which are corrected with an STC'd stainless steel patch strap worked-in between the outer skin and the door post.

I wonder how Cessna will correct this current design flaw?
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
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Re: New AD (lwr strut/doorpost area) NOT Applicable to 170s.

Post by n2582d »

Gary
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