Airworthiness Directive · Amendment 39-11992 · Saab Model SAAB SF340A and SAAB 340B Series Airplanes
Saab Model SAAB SF340A and SAAB 340B Series Airplanes
Model SAAB SF340A series airplanes, manufacturer's serial numbers -004 through -159 inclusive; and SAAB 340B series airplanes, manufacturer's serial numbers -160 through -459 inclusive; certificated in any category; on which any flap assembly having part number (P/N) 7257800-501 through 508 inclusive, or 7257800-851 through 7257800-856 inclusive, is installed.
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 supersedes an existing airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, that currently requires inspections to detect damage or cracking of the forward and aft attachment lugs of the flap fittings at wing station (WS) 123.38; an inspection to verify that the sizes of the holes of the flap fittings are within specified limits and to ensure that the swaged bushings are not loose; and modification of the flap fittings. This amendment requires repetitive accomplishment of the inspections using improved inspection methods; a one-time visual and repetitive general visual and detailed visual inspections; new repetitive non-destructive test (NDT) inspections; and corrective and follow-on actions, as necessary. This amendment also provides for terminating action for all repetitive inspections and revises the applicability of the existing AD. The actions specified by this AD are intended to prevent high bearing stress on the bushings of the flap fittings, which could result in wear on the bushings, cracking of the flap fittings, and breakage of the lugs; these conditions could result in jamming of the flaps and consequent reduced controllability of the airplane.
To prevent high bearing stress on the bushings in the flap fittings, which could result in jamming of the flaps and consequent reduced controllability of the airplane, accomplish the following:
(a) Within 800 flight hours after the effective date of this AD, perform a one-time visual inspection of the flap assemblies of the flap fittings at wing station (WS) 123.38 to determine the flap assembly serial numbers, in accordance with Saab Service Bulletin 340-57-035, dated January 18, 2000.
(1) If none of the serial numbers of the flap assemblies are listed in the service bulletin, no further action is required by this paragraph.
(2) If the serial number of any flap assembly is listed in the service bulletin, prior to further flight, accomplish the requirements of paragraph (a)(2)(i) and, at the time specified, accomplish the requirements of paragraph (a)(2)(ii) of this AD.
(i) Perform a general visual inspection of the affected flap fittings at WS 123.38 to detect cracking, in accordance with the service bulletin. If no cracking is detected, repeat the visual inspection thereafter at intervals not to exceed 800 flight hours, until the requirements of paragraph (a)(2)(ii) of this AD are accomplished. If any cracking is detected, prior to further flight, accomplish the terminating action specified by paragraph (c) of this AD.
(ii) Within 4,800 flight hours after the effective date of this AD, perform a one-time detailed visual inspection of the flap fittings to determine the size of the inboard and outboard holes (swaged bushing) and to detect loose swaged bushings; and perform an NDT inspection of the aft attachment lugs of the flap assemblies at WS 123.38 to detect cracking, in accordance with the service bulletin. Accomplishment of the NDT inspection terminates the general visual inspection required by paragraph (a)(2)(i) of this AD.
Note 2: For the purpose 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.”
Note 3: For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirrors, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”
(A) If all the hole sizes are within the limits specified by the service bulletin, no loose swaged bushings are found, and no cracking of the aft attachment lugs is detected: Prior to further flight, install new fasteners that attach to the flap hinges (nuts, bolts, bushing, and washers), in accordance with the service bulletin.
(B) If any hole size is outside the limits specified by the service bulletin, or any loose swaged bushing is found, or any cracking is detected on the aft attachment lugs: Prior to further flight, accomplish the terminating action specified in paragraph (c) of this AD.
(b) Within 800 flight hours after the effective date of this AD, perform a one-time visual inspection of the aft attachment lugs (flap assemblies) of the flap fittings at wing station (WS) 123.38 to determine the flap assembly modification status, in accordance with Saab Service Bulletin 340-57-037, dated January 18, 2000.
(1) If the modification status is such that all flap assemblies installed have thicker lugs, as specified by Figure 1 of the service bulletin, no further action is required by this paragraph.
(2) If the modification status is such that any flap assembly installed has a thinner lug, as specified by Figure 1 of the service bulletin, prior to further flight, accomplish the requirements of paragraph (b)(2)(i) and, at the time specified, accomplish the requirements of paragraph (b)(2)(ii) of this AD.
(i) Perform a general visual inspection of the aft attachment lugs of the flap fittings at WS 123.38 to detect cracking or damage, in accordance with the service bulletin. If no cracking or damage is detected during the visual inspection, repeat the inspection thereafter at intervals not to exceed 800 flight hours, until the requirements of paragraph (b)(2)(ii) of this AD are accomplished. If any cracking or damage is detected during any general visual inspection required by this paragraph, prior to further flight, accomplish the terminating action specified by paragraph (c) of this AD.
(ii) Within 6,000 flight cycles after the effective date of this AD, perform an NDT inspection of the aft attachment lug of the flap fittings at WS 123.38 to detect cracking, in accordance with the service bulletin. Accomplishment of the NDT inspection terminates the repetitive visual inspections required by paragraph (b)(2)(i) of this AD. If no cracking is detected, repeat the NDT inspection thereafter at intervals not to exceed 6,000 flight cycles, until the actions specified by paragraph (c) are accomplished. If any cracking is detected during any NDT inspection required by this paragraph, prior to further flight, accomplish the terminating action specified by paragraph (c) of this AD.
(c) Replacement of all flap fittings at WS 123.38 with new, improved flap fittings in accordance with Saab Service Bulletin 340-57-038, dated January 18, 2000, terminates all inspections required by 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
