Dave Siciliano
Final Approach
Ladys and Gents:
There is a good article discussing the state of the AD on the Cessna 400 Series and the fix in Twin & Turbine Mag (October). For those of you that get it. Goes through the inspections and fixes.
The article ends by saying that the owner of one repair station interviewed (Pickett of Yingling) believes Cessna will issue a Service Bulletin regarding spar strap modification for all 300 series twins except the 337 Skymaster shortly and all 400 series twins except the Model 404 and 441.
The current modification being installed by Yingling costs $33,200 to 48,400 and takes about four weeks.
More on the issue from Mike Busch:
Cessna did that for the 300-series aircraft some time ago. The question is whether or not they'll ask the FAA for an AD. No 300-series owner in his right mind would install the spar strap modification unless compelled to do so by AD.
Note that there has NEVER been a single documented case of any wing spar fatigue crack or failure in ANY twin Cessna model other than the model 402. The only 402s with a history of cracks (approximately 1/2 dozen aircraft) were aircraft that were extremely high-time, extremely high-cycle, and (most significantly) operated with extremely high cabin loads and extremely low fuel loads (i.e., very high zero-fuel weight). Since it is highly unlikely that any other twin Cessna model besides the 402 is capable of operating in such a fashion, I believe it highly unlikely that any other Cessna model will ever experience fatigue cracking of the wing spar during the useful life of the airplane.
The Cessna 401 is 100% identical to the Cessna 402 except that the
401 was fitted with an executive interior and the 402 with a high-density passenger interior. There has never been a single reported instance of a fatigue crack in a 401 wing spar, while there have been a significant number of such cracks in 402 wing spars. The hardware is identical; the loading and usage is radically different.
I believe that the current spar strap AD is appropriate as it applies to Cessna 402 aircraft, as there is a demonstrated unsafe condition with these aircraft when operated in a high-cycle high-ZFW regime. I also consider that it is a travesty that the same AD applies to
non-402 models, especially the pressurized 414A. There is no possibility that any 414A will ever operate in the high-cycle, high-time, high-ZFW regime that produces spar cracking. Sadly, we were not able to persuade the FAA of this despite a best-efforts full-court press.
I spent several years immersed in this subject as the Cessna Pilots Association point person on the spar strap AD matter, and authored CPA's extensive docket comments and oral testimony at the FAA public meetings.
There is a good article discussing the state of the AD on the Cessna 400 Series and the fix in Twin & Turbine Mag (October). For those of you that get it. Goes through the inspections and fixes.
The article ends by saying that the owner of one repair station interviewed (Pickett of Yingling) believes Cessna will issue a Service Bulletin regarding spar strap modification for all 300 series twins except the 337 Skymaster shortly and all 400 series twins except the Model 404 and 441.
The current modification being installed by Yingling costs $33,200 to 48,400 and takes about four weeks.
More on the issue from Mike Busch:
Cessna did that for the 300-series aircraft some time ago. The question is whether or not they'll ask the FAA for an AD. No 300-series owner in his right mind would install the spar strap modification unless compelled to do so by AD.
Note that there has NEVER been a single documented case of any wing spar fatigue crack or failure in ANY twin Cessna model other than the model 402. The only 402s with a history of cracks (approximately 1/2 dozen aircraft) were aircraft that were extremely high-time, extremely high-cycle, and (most significantly) operated with extremely high cabin loads and extremely low fuel loads (i.e., very high zero-fuel weight). Since it is highly unlikely that any other twin Cessna model besides the 402 is capable of operating in such a fashion, I believe it highly unlikely that any other Cessna model will ever experience fatigue cracking of the wing spar during the useful life of the airplane.
The Cessna 401 is 100% identical to the Cessna 402 except that the
401 was fitted with an executive interior and the 402 with a high-density passenger interior. There has never been a single reported instance of a fatigue crack in a 401 wing spar, while there have been a significant number of such cracks in 402 wing spars. The hardware is identical; the loading and usage is radically different.
I believe that the current spar strap AD is appropriate as it applies to Cessna 402 aircraft, as there is a demonstrated unsafe condition with these aircraft when operated in a high-cycle high-ZFW regime. I also consider that it is a travesty that the same AD applies to
non-402 models, especially the pressurized 414A. There is no possibility that any 414A will ever operate in the high-cycle, high-time, high-ZFW regime that produces spar cracking. Sadly, we were not able to persuade the FAA of this despite a best-efforts full-court press.
I spent several years immersed in this subject as the Cessna Pilots Association point person on the spar strap AD matter, and authored CPA's extensive docket comments and oral testimony at the FAA public meetings.
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