Cessna C337 SID

[K337A]

- Mr Truman Sparks and his fine flying machine. Best line in the film as he picks up the chicken ...."No flying today Agnes". Then Mr. Sparks does a a little field approved Duct tape repair. Aircraft is now owned by Randy Deluca's son. Still fly's it out in California.

[edasmus]

Thanks for the info gentlemen. I tell ya, I must be getting old and crabby, but between the FAA (who happens to be my employer incidentally), the TSA, Cessna, and others, flying my Skymaster on a sunny day to play a round of golf is getting to be more and more challenging. It shouldn't be so complicated.

Thanks again! Ed

[WebMaster]

I couldn't agree with you more Ed. Just be thankful you weren't planning on going to Martha's Vineyard real soon.

[Ernie Martin]

The two links contained in one of the above messages were very informative.

The one important element that may be pertinent to the upcoming meetings and where we have critical data to contribute is cabin weight.

This is somewhat simplified, but in the first of the two links, Mike Busch makes the case that Cessna's analysis seems to have assumed large cabin loads and low fuel loads in the stress analysis, yielding fatigue lifes which are much shorter than if it had assumed low cabin loads and high fuel loads*. I believe that 337s are mostly operated with low cabin loads (often with 1 or 2 occupants) and often on long-endurance surveillance missions (with large fuel loads). I know that I never use my 5th and 6th seats. We must try to get Cessna to consider this, which will result in much longer safe life if the 337 wing structure and stress distribution bears some similarities to the 400 series.

Ernie

* "The tensile stress on the critical wing main spar elements is a function of cabin load (i.e., zero-fuel weight), not of gross weight. In fact, fuel weight (which is outboard of the “ hot” region) actually reduces the stress. It turns out that fatigue life is exquisitely sensitive to changes in tensile stress—a small reduction in stress can result a big increase in safe life" (abreviated excerpt). Yet Cessna proposed the same safe life for the 401 models (which came with seating for 6) and for the 402 models (which came with higher-density seating of up to 11 passengers). And Cessna did this despite the fact that "there are six known instances of 402s with cracked spars, but no known instances of 401s with cracks."

[Skymaster337B]

I'd like to talk to the Cessna folks about their SID plans. Who is the contact over there at Cessna? Even if I can't visit in person, perhaps teleconference or phone interview. My other question is why does Cessna even care about 337's any more? It must cost them allot of money to worry about old Skymasters...especially since we can't sue them any more since all Skymasters are over 20 years old (Federal law). My point is I smell a rat. Does Cessna have a plan to shake us all down for "Life Extension Kits".

[Ernie Martin]

For a background on why this is being done, read the first of the two links in the 3rd message from K337A.

Ernie

[Paul462]

Amigos,

AOPA responded thusly to an inquiry about what they knew about the proposed 336/337 SID:

Paul,

John Collins asked me to respond to your question on the Cessna SID program. The Cessna SID program goes back a few years as you mention below and Cessna is working on developing SID programs for most of their fleet. For the majority of operators complying with Cessna SIDs is not mandatory.

The recent issue with the C-425/441 SID surrounded the fact that those aircraft fall under FAR 91.409(e) and (f) and have to be on an approved maintenance plan. Most C-442/441are maintained on the Cessna factory plan, as these plans meet the requirements for 91.409. When Cessna updated their maintenance plan to include the SID these owners asked for clarification of their regulatory responsibility under 91.409, and in some cases the SID is required.

Because the Cessna 337 does not meet the requirements of FAR 91.409(e) a Cessna SID would not be mandatory for owners/operators of these aircraft. I've include 91.409(e) and (f) below. I hope this helps.

e) Large airplanes (to which part 125 is not applicable), turbojet multiengine airplanes, turbopropeller-powered multiengine airplanes, and turbine-powered rotorcraft. No person may operate a large airplane, turbojet multiengine airplane, turbopropeller-powered multiengine airplane, or turbine-powered rotorcraft unless the replacement times for life-limited parts specified in the aircraft specifications, type data sheets, or other documents approved by the Administrator are complied with and the airplane or turbine-powered rotorcraft, including the airframe, engines, propellers, rotors, appliances, survival equipment, and emergency equipment, is inspected in accordance with an inspection program selected under the provisions of paragraph (f) of this section, except that, the owner or operator of a turbine-powered rotorcraft may elect to use the inspection provisions of §91.409(a), (b), (c), or (d) in lieu of an inspection option of §91.409(f).
(f) Selection of inspection program under paragraph (e) of this section. The registered owner or operator of each airplane or turbine-powered rotorcraft described in paragraph (e) of this section must select, identify in the aircraft maintenance records, and use one of the following programs for the inspection of the aircraft:

Have a good weekend,
Leisha


Leisha Bell
Director, Aircraft and Environment

Aircraft Owners and Pilots Association

Ph: 301-695-2086

Fax: 301-695-2214

Leisha.Bell@aopa.org

www.aopa.org



Whether the FAA proceeds to require compliance by AD (as occured with the 400 series twin Cessnas), and/or whether insurance companies will attempt to encourage compliance, are different questions.

Therofer, it behooves us to pay close attention to this developing saga.