Thread: Cessna C337 SID
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Unread 10-03-09, 12:09 PM
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Cessna SID Update

This provides an update on the 23 draft Cessna Supplemental Inspection Reports (SIDs) being considered for the Skymaster. If you have read prior messages in this thread you know that Cessna presented these draft SIDs to SOAPA at a meeting on Aug. 27, 2009. Also in attendance at this meeting, beyond SOAPA, were other technical specialists and Skymaster experts, representing themselves. Cessna outlined the proposed draft SIDs at this meeting. SOAPA has requested permission to distribute the draft SIDs but Cessna appears reticent, perhaps because they remain in draft form and are under further consideration within Cessna. Our understanding of the SIDs, as proposed, is that they would not be required for Part 91 operators, but will be for Part 135 and international operators.

The proposed SIDs may be lumped into the following broad groups: fuselage, wing, tail, and engine groups. While some of the proposed SIDs are minor and would normally be easily accessible and be part of an annual inspection, many are significantly more comprehensive and invasive to the airframe. The fuselage SIDs call for visual inspection of the rear spar carry-through and upper rear doorpost bulkheads, nose gear torque link, rudder pedal area, and door lock mechanism. As presently proposed, the wing SIDs involve eddy current inspections of the wing attach bolts area which may require substantial disassembly of the aircraft to complete. Other proposed work on the wings involves removal of fixed panels to gain access to high stress areas for eddy current inspection; and loosening and inspection of the flap cables.(eg jack points, wing strut attach points, aileron hinges). The proposed tail section SIDs require removal of the rudders and elevator for eddy current inspection of the hinge attach fittings among other inspections required once disassembled. As proposed the engine mount SID calls for removal of the tubular engine mounts for inspection. Importantly, as proposed the entire SID package would have a compliance time of 20 (twenty) years from date of aircraft manufacture and every 10 (ten) years thereafter, with varying TTAF hour triggers for certain SIDs. The SOAPA sub-committee investigating this matter has looked at preliminary cost estimates for compliance of various of these proposed SIDs. As proposed the compliance cost would be substantial (exceeding $20,000 or more) and take a considerable amount of time. We would caution members that these estimates are early and based on non-final Cessna documents. If the final Cessna SIDs are modified or allow for alternate means of compliance or inspection, or some are eliminated entirely, then these estimated compliance costs could be substantially less.

SOAPA has organized a Steering Committee (the “Committee”) to address this matter with Cessna. The Committee includes engineers and other technical professionals (A&P, IA) highly experienced with Skymasters and other interested owners. In addition, the Committee has called on others outside the Committee with similar experience (including an FAA DER in structures who has owned 4 Skymasters in the last 20 years) for additional advice and assistance as necessary.

Committee members began a comprehensive review of the FAA Service Difficulty Reports (“SDRs”) for over 35 years of problem reports furnished to the FAA by repair shops. The SDRs have been a focus of Committee work because Cessna has used the SDRs as one of the key sources of information in the development of its proposed SIDs for the Skymaster series of aircraft. First, SOAPA filtered to entire SDR database to extract those dealing only with Skymasters. The resulting 1,773 SDRs were further analyzed and those having nothing to do with the SIDs, fatigue, corrosion or aging aircraft were deleted. The remaining SDRs (over 200) were then arranged by aircraft area and further analyzed against the proposed SIDs presented by Cessna. Each SID was also analyzed in terms of the hardware involved, eg. is this likely where failure would occur, could the proposed inspection result in more harm than good to the airframe?

At this point in time the Committee has not fully completed our examination of the SIDs nor have we submitted final comments to Cessna. To date we have identified a number of areas where we believe compelling engineering arguments exist for us to recommend either deletion or a substantial reduction in the scope of the related SID. Cessna has gone out of its way to solicit our views and has stated that their upper management wants this SIDs to be “for the benefit of the fleet”. We are hopeful that our findings will lead to SIDs which are far less burdensome than the draft versions, but this remains to be seen and will depend on future meetings with Cessna.

The Committee is also reviewing the matter of the 20-year from manufacture compliance period, which for Skymasters will mean immediate compliance for certain operators who are required to comply or for those owners wishing to voluntarily comply with the SIDs. This same 20 year time trigger was used in the SIDs issued previously by Cessna for the 400-series aircraft (despite opposition by 400-series owners and operators and the repair corporation they formed and funded to address compliance). However, in our case, the Committee believes that there are grounds for recommending to Cessna that this provision be modified for Skymasters. Work on this matter continues.

At this time we are in the process of finalizing our analysis of the SIDs and formulating a report for Cessna. Cessna engineering staff are scheduled to visit a Skymaster service shop that has aircraft in various states of disassembly for inspection. This will allow Cessna to consider the proposed SIDs and possible alternate inspection approaches to address the areas of concern with the benefit of actual disassembled aircraft to examine. SOAPA will have a representative at this meeting as well. We expect to fold any developments that come out of that meeting into our report and are targeting to have our report provided to Cessna by mid October.

We will keep you informed of any further developments or changes to the above as soon as we are able. Should you have any input that you would like to provide to the SOAPA Committee members working on this matter please provide this directly to SOAPA President, Herb Harney hharney@sbcglobal.net or reply openly to this thread.

Last edited by hharney : 10-06-09 at 04:42 PM.
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