Cessna C337 SID

[Ernie Martin]

Further to Herb's message above, the Supplemental Inspection Document addresses inspections and modifications required for aging aircraft to remain airworthy. The most infamous is the one for 402 Cessnas, which for aircraft with over 15,000 hours requires the installation of wing-spar straps in a procedure that is so expensive that it threatens grounding much of the fleet. Cessna is now working on other models, including the 337.

But please note:

1. The 402s are low-wing aircraft with wing mounted engines and some have a dry wing with the fuel in tip tanks, so the loads at the root of the wings are quite different than for a 337.

2. Many (most?) of the 400s have spent much of their life in charter operations, accumulating thousands of hours per year, so fatigue cycles are much greater than for the typical 337.

It's possible that the difference in loads and designs will result in an SID for the 337 which is considerably less costly and may be applicable even later in life (say, 25,000 hours). Since most 337s have far less hours, few aircraft may be affected over the next decade.

But we need to stay on top of this.

Ernie Martin

[WebMaster]

The SID program calls for inspections. It is no different than the requirement for wing spar x-rays on Beech 18's, or the spar inspection or other mandatory service bulletins for twin commanders. While Ernie is correct that it has been applied to 402's, it has also been applied to 414's, and the 425 and 441 turbo props. On the 441's, they determined that the fleet averaged 8000 hours. The initial requirement for the SID was extremely invasive. It consumed so many hours that the centers that could do the SID were overloaded, and they extended and modified the requirements. Incidentally, the initial SID for 425's was anticipated to cost $150K to $250K, depending on the findings.


Cessna has obviously decided to extend the program to other aircraft. The initial implementation may not be the final outcome. As Ernie says, it's important to stay on top and be aware.

Between now and the initial implementation, the input from users should have a major impact on how it is implemented. It behooves everyone to be as involved at this point as possible. If you live in Kansas, or would like to be involved in the discussions, please send Herb an email.