Continental Airlines Inc.

1. The revised proposed rule drastically reduces the initial external inspection threshold for operators like Continental whose typical flight profile is low cycle/high flight hours per day. Note: Continental average total fleet cycle is 5000 with average total flight hours of 28,000. Per the information provided in (page 27 of) the S/B this drastic reduction in initial inspection threshold does not seem to be justified as all the reported cracks have been on aircraft with moderate (13,000+) to high (20,000+) to very high (37,000+) total flight cycles. And in all cases except one all the findings have been on airplanes with moderate (44,000+) to high (67,000+) flight hours. And in the case of that one aircraft with high flight cycle (20,000+) and low hours (<23,000 hours), obviously cyclic stresses have played a major role as the data suggests. So in the revised NPRM if the FAA would prefer to introduce the flight hours into the equitation as a factor for determining the initial external inspection threshold, CAL proposes paragraph (f)(1) of the revised NPRM to read; Prior to accumulation of total 10,000 flight cycle or 50,000 total flight hours, whichever occurs first. 2. It appears the intent of the S/B in part 1 of the work instruction is to detect any crack propagating from the two forward tension bolt holes of the diagonal brace aft pitch fitting. However, in the related inspection figures of the S/B, the area of the inspection is much beyond the two bolt hole areas. It is unclear to CAL the reasoning behind such an expanded area of inspection. If Boeing anticipates possible fall out on the wing lower skin in areas other than the two bolt hole, part 2 of the work instruction should have provide some disposition for such possible findings or at least included an statement to contact Boeing for further disposition. As it stands now part 2 work instruction provides disposition for any finding around the two bolt hole areas only.