Airworthiness Directive · Amendment 39-11785 · Saab Model SAAB SF340A and SAAB 340B Series Airplanes
Saab Model SAAB SF340A and SAAB 340B Series Airplanes
Model SAAB SF340A, serial numbers -004 through -159 inclusive; and SAAB 340B series airplanes, serial numbers -160 through -444 inclusive; certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment adopts a new airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, that requires a one-time inspection to detect corrosion and scratches on the bearing housing surfaces of the support assembly on the main landing gear (MLG), and corrective actions, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent corrosion in the inboard and outboard bearing housings of the MLG support assembly, which could result in fatigue cracks in the support assembly and lead to failure of the MLG.
To prevent corrosion in the inboard and outboard bearing housings of the support assembly of the main landing gear (MLG), which could result in fatigue cracks in the support assembly and lead to failure of the MLG, accomplish the following:
(a) At the applicable time specified in paragraph (a)(1), (a)(2), (a)(3), or (a)(4) of this AD: Perform a one-time general visual inspection of the eight bearing housing surfaces of the MLG to detect corrosion or scratches, in accordance with Saab Service Bulletin 340-57-036, dated October 20, 1999.
(1) For airplanes with 32,000 or more total flight cycles as of the effective date of this AD, the inspection is to be performed within 4,000 flight cycles after the effective date of this AD.
(2) For airplanes with 24,000 or more and fewer than 32,000 total flight cycles as of the effective date of this AD, the inspection is to be performed within 6,000 flight cycles after the effective date of this AD.
(3) For airplanes with 12,000 or more and fewer than 24,000 total flight cycles as of the effective date of this AD, the inspection is to be performed prior to the accumulation of 24,000 total flight cycles, or within 6,000 flight cycles after the effective date of this AD, whichever occurs later.
(4) For airplanes with fewer than 12,000 total flight cycles as of the effective date of this AD, the inspection is to be performed prior to the accumulation of 12,000 total flight cycles, or within 6,000 flight cycles after the effective date of this AD, whichever occurs later.
Note 2: For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”
(b) Except as provided by paragraph (c) of this AD: If, during the inspection required by paragraph (a) of this AD, any corrosion or scratch is detected that is within the limits specified in Saab Service Bulletin 340-57-036, dated October 20, 1999, prior to further flight, perform corrective actions (including rework, an eddy current inspection, and repair) in accordance with Steps 2.B. and 2.C. of the Accomplishment Instructions of the service bulletin.
(1) If, after rework, the depth of the damage is less than or equal to 0.15 mm (0.006 inches) AND the damage does not exceed 15 percent of the area, no further action is required by this AD.
(2) If, after rework, the depth of the damage exceeds 0.15 mm (0.006 inches) but is less than or equal to 1.1 mm (0.043 inches), AND the damage does not exceed 30 percent of the area: Within 4,000 flight cycles after accomplishment of the inspection required by paragraph (a), repair the MLG support assembly in accordance with the service bulletin. Following the repair, no further action is required by this AD.
(c) If, during any inspection required by this AD, a discrepancy is detected for which the service bulletin specifies to contact Saab for appropriate action [including any crack or any corrosion or scratch that exceeds 1.1 mm (0.043 in) after applicable rework has been performed as required by paragraph (b) of this AD]: Prior to further flight, repair in accordance with a method approved by the Manager, International Branch, ANM-116, Transport Airplane Directorate; or the Luftfartsverket (LFV) (or its delegated agent). For a repair method to be approved by the Manager, International Branch, ANM-116, as required by this paragraph, the Manager's approval letter must specifically reference this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
