Lady Legs on an A model

How to keep the Cessna 170 flying and airworthy.

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ErikW
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Lady Legs on an A model

Post by ErikW »

Based on a search, I realize this topic has been covered somewhat in the past, but…

I’m currently in the process of having the original A model landing gear swapped out to “lady legs.” The A&P I’m working with wants to go through the 337 process and says the FAA is more open to accept it if it has already been approved previously (and even better if more than once). I’m very interested in any input from the group, but I’m particularly interested in speaking to any members who have previous experience with the paperwork of this particular install.

Thank you,

Erik
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n2582d
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Re: Lady Legs on an A model

Post by n2582d »

Erik,
Your mechanic will find it a lot easier to use the Association’s STC SA01756NY than to go the field approval route.

I see that there is a typo on that STC. The FAA left out one “1” on p/n 0541118-3 and again on p/n 0541118-2.
Last edited by n2582d on Sun Aug 12, 2018 12:18 am, edited 1 time in total.
Gary
ErikW
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Re: Lady Legs on an A model

Post by ErikW »

Thank you for the quick reply Gary.

I’m currently traveling and don’t have access to part numbers of the Lady Legs. I was under the impression the Association held the STC for the installation of 180 gear on the 170. However, if this STC is usable for Lady Legs as well, it would certainly make things much simpler. Thanks again,

Erik
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Bruce Fenstermacher
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Re: Lady Legs on an A model

Post by Bruce Fenstermacher »

The STC is NOT for lady legs on aircraft prior to serial 25612. I'd venture to say most early 170s with lady legs where done with a simple log entry with the feeling they would be the superseding part for the early gear.

Interesting, the change in gear came mid production year '53. That means there are as many 170Bs with early gear as 170Bs with lady legs. And there was no change to any limits, weight, or gross weight. Kind of reminds some folks of a minor alteration since it doesn't meet many of the requirements, if not all, of a major alteration which requires a 337.

I'd think your mechanic and you might be best served first taking the position this is a minor alteration, but wanted to run that by their PI. Maybe the PI will agree, maybe he won't, but if you act like this is a major alteration by filing out a 337 your taking the position you think it is and the PI is likely to agree and you not likely to want to jump through the hoops of paying a DAR to tell the FAA its OK.

You might find a 337 in our library documenting the change if you look but that does not mean in any way this is a major alteration. It means someone at a time when it was easy to get these things approved by the Fed, covered their butt.
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n2582d
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Re: Lady Legs on an A model

Post by n2582d »

Bruce Fenstermacher wrote:The STC is NOT for lady legs on aircraft prior to serial 25612. ... .
Bruce, If that’s the case the description seems poorly written. The STC covers the Cessna 170, 170A, 170B, and 180. It reads,
Description of Type Design Change:
Installation of Cessna Main Landing Gear Legs P/N 0741001-1 through-8 and 054118-2 though -3 in accordance with Installation Instructions CI-ECL-001, Rev Original, Transport Canada approved on June 4, 2003.
Why are the lady leg part numbers, 0541118-2 and -3, included in the STC?

But I do agree with you that installing the lady leg gear should just be a minor alteration.
Gary
ErikW
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Re: Lady Legs on an A model

Post by ErikW »

Interesting point in the part numbers Gary. Thanks for the breakdown, Bruce.

Erik
hilltop170
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Re: Lady Legs on an A model

Post by hilltop170 »

Eric-
Based on the previous posts, I would call Jan and have her email you a review copy of the complete STC including the approved models/gear. Let your IA look it over and if he agrees you are covered, buy the STC from the club and have your IA fill out the installation 337 (this is not a field approval and does not need FAA sign-off in Block 3, it just documents installation of the STC which is already FAA approved) with "Installed p/n 0541118-3 and 0541118-2 main landing gear in accordance with STC SA01756NY." Then he should make a log book entry stating the same thing.

Done deal!
Last edited by hilltop170 on Tue Aug 14, 2018 11:22 pm, edited 1 time in total.
Richard Pulley
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1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
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Bruce Fenstermacher
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Re: Lady Legs on an A model

Post by Bruce Fenstermacher »

Gary, you are right. Our STC does cover installation of lady legs on early 170s. I'm glad you guys are around to keep me straight when I forget such detail and once again I will renew my effort to look up every detail before I comment about it.

Richard, if you show the Fed our STC or mention our STC, you will not get approval for the 337 from the Feds for it. Without approval of some kind a 337 is worthless. Might as well just make a log entry. No one can use our STC without the associations written approval which of course cost money.

If a mechanic thinks this change may be a major alteration, and it sounds like this mechanic does, our STC is cheap enough to buy, virtually can not be denied or ever questioned.
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Re: Lady Legs on an A model

Post by Bruce Fenstermacher »

Richard, rereading your post I read it different the first time. What was missing is the STC must be bought before it can be used as approval on a 337.
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n2582d
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Re: Lady Legs on an A model

Post by n2582d »

Bruce, I'm as surprised as you are to see that our STC is for the lady legs as well as the 180 gear. I was going to install the lady legs I bought as a minor alteration but now I'll be calling HQ to buy the STC. Down the road no one will question the legality of the later style gear on my '52. CYA.
Gary
ErikW
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Re: Lady Legs on an A model

Post by ErikW »

Thank you everyone again. I’m still new to aircraft ownership and this has been very educational. What a wealth of knowledge on this site! I’m going with Gary and Richard’s suggestion of using the STC. Seems like a no brainer to keep everything clean and legal.

Erik
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Bruce Fenstermacher
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Re: Lady Legs on an A model

Post by Bruce Fenstermacher »

Erik, now that we got what the STC can cover cleared up, you've come to the right conclusion for you. It is easy and a no brainier, but it does involve the cost of the STC. In any likely hood trying not to use the STC or if there was no STC, you cost would be higher in mechanic fees due to consulting time with the FAA and maybe even a Designated Engineering Representative.

You should understand that all our advice before Gary mentioned the STC is still valid. Many do not consider this change a major alteration and thus it would be a minor alteration. Minor alterations do not require the same bases of approval as a major. There have been many 170 owners, in a time long gone, who simply asked the local FAA who had more knowledge about aircraft, and they received approval. Most of the ability of the local FAA to do this today has been removed. Still some mechanics today, mostly those with old time experience, and not afraid of the FAA, will make their own judgement that this is a minor, but those mechanics are few and far between today.

Of course many today argue that since the FAA granted a STC for this, it could not be a minor alteration. Whether it is a major or minor alteration has no relevance on the creation and issuance of an STC.
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ErikW
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Re: Lady Legs on an A model

Post by ErikW »

Bruce, thanks for the clarification. With my limited exposure to these issues, I tend to agree with classifying this one as a minor alteration. It is a CYA world we live in, particularly in avaiation, and I’m glad there is a simple solution. This whole process has been a little bit of a struggle but now I can finally see my plane coming back from the shop!

Erik
hilltop170
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Re: Lady Legs on an A model

Post by hilltop170 »

By using the STC, the question is settled for all time. If one IA considered it a minor alteration this year with a logbook entry and you didn't use the STC, a different IA might consider it a major alteration next year and you would be faced with going thru the whole exercise again. That concern is settled since the FAA has approved the STC and taken the decision responsibility out of the IA's hands.
Richard Pulley
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1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
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Bruce Fenstermacher
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Re: Lady Legs on an A model

Post by Bruce Fenstermacher »

hilltop170 wrote:By using the STC, the question is settled for all time.
Well, not really for all time but as close as one can get. The FAA could decide to rescind the STC and have all mods covered by it removed but this has rarely, if ever, been done.
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