Fatigue Critical Baseline Structure List for Cessna 560
Fatigue Critical Baseline Structure List for Cessna 560
(OP)
Does anyone have the fatigue critical baseline structures list for the Cessna 560. I am not sure one exists. This list will identify principle structural elements of the airplane that would require damage tolerance evaluation when modified or repaired





RE: Fatigue Critical Baseline Structure List for Cessna 560
if this is for an STC you're doing (and you're looking for a definition of primary structure), that is probably more generic (wing, fuselage, empennage, ...).
note that the TC shows that the Citation is not a damage tolerant a/c (they're at rev 25.17)
RE: Fatigue Critical Baseline Structure List for Cessna 560
Hopefully Cessna didn't do the same thing, but it is safe to assume they did.
RE: Fatigue Critical Baseline Structure List for Cessna 560
RE: Fatigue Critical Baseline Structure List for Cessna 560
RE: Fatigue Critical Baseline Structure List for Cessna 560
RE: Fatigue Critical Baseline Structure List for Cessna 560
RE: Fatigue Critical Baseline Structure List for Cessna 560
i'd suggest you consider carefully before committing to doing DTA. if the plane doesn't have a mandatory structural inspection manual, then it almost certainly won't have defined inspection procedures. in my experience using an OEM's inspection technique beats the heck out of creating (and proving) your own. mind you your plane is probably a "hangar queen" (no slight implied) and the design life goal is short (compared to a workin' plane) so you may be able to get away with a "non-inspectable" result (the USAF permits you not to inspect a location if the threshold interal > 2*service life, normally the FAA doesn't).
RE: Fatigue Critical Baseline Structure List for Cessna 560
Since it's on an airplane it is going to have some kind of inspection, and the 560 indeed does have a nice phase inspection program. Cabin door frame is every 1200 hours or 36 months. The trick is to do a design that remains inspectable, and have an analysis that shows these existing inspections remain appropriate.
Something else that may sway your approach: the 560 has Special Conditions (25-ANM-31) which would apply if your repair involves the pressure vessel boundary. DT makes compliance much easier.
RE: Fatigue Critical Baseline Structure List for Cessna 560
i'd say the difference with fatigue analysis is that if the factored safe life exceeds the design life then no limitation is imposed, always.
do the special conditions in ICAs ? i'd think this'd be a little odd (since it isn't a DT (admt 45) airplane).
RE: Fatigue Critical Baseline Structure List for Cessna 560
Subsequent inspections are then defined by (N-critical - N-detectable)/3 so that you get at least 2 inspections between the time you are supposed to be able to detect the crack and the time when it fails catastrophically.
RE: Fatigue Critical Baseline Structure List for Cessna 560
RE: Fatigue Critical Baseline Structure List for Cessna 560
I have to admit that I'm not a DER (yet), so DER8110 may have better knowledge and different guidelines. My information comes from a close relationship with a DTA DER, and I believe she follows the FAA pretty closely. She attends the various DTA seminars hosted by the FAA and argues with them about things with which she disagrees until she finally submits to their requirements
RE: Fatigue Critical Baseline Structure List for Cessna 560
rb: I may have been too brief about Special Conditions. They are for "high altitude aircraft" of which the 560 is one. Nowadays the requirements are part of regulation, amendment 25-87. Read the preamble for some background. Basically whenever "high altitude" applies there needs to be a leakage analysis through cracks propagating over four (and number can vary) inspection intervals. So what better way to know how long/wide your crack is than by DT (LEFM). Fatigue can't get you that. So depending on the analytical results, there may or may not be anything to go into the ICA. Rarely see leakage driving any maintanance, even on a small cabin like a 560. There are going to be standard hull checks anyway; that is when cracks are typically found.