1AD/DHC-8/8 Amdt 4 - Flap Drive and Torque Sensing Systems

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Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes

AD/DHC-8/8

Amdt 4

Flap Drive and Torque Sensing Systems 11/94

Applicability: Model DHC-8 series, serial numbers 3 and subsequent, as indicated.

Requirement: Part I. For aircraft serial numbers 3 through 177, and serial numbers 178 through 231, 233, 235, 237, and 243:

(a) Locate flap primary-drive torque tubes having part numbers and serial numbers listed in revised table 1 below:

TABLE 1

TORQUE TUBE P/N SERIES TORQUE TUBE S/N

734187 125 through 171

734378 129 through 150

734380 127 through 166

734382 211 through 322

734384 153 through 188 and 226 through 235

734386 195 through 286

734388 160 through 177

(b) Determine whether torque tubes located by 1.(a) above have been re-identified with the service bulletin number indicated in Table 2 below.

Note: For re-identification, the applicable service bulletin number may have been marked on the rod with indelible ink or on the identification plate adjacent to the part number.

(i) Torque tubes found to have been re-identified with the applicable service bulletin number do not require further action per Part 1 of this Directive.

(ii) Torque tubes not re-identified with the applicable service bulletin number must be inspected and reworked as required by Part I, Requirements 1(c) and (d), and 2 below.

(c) On the torque tubes located per Requirement 1.(b)(ii) above, remove the through bolt from the splined coupling(s) of each torque tube and, using a 10x magnifying glass, visually inspect the area around all holes for cracks.

Note: Some torque tubes have one splined coupling, while others have two. If a splined coupling is found cracked, accomplish one of the following steps before further flight:

(i) Replace the splined coupling(s) in accordance with the accomplishment instructions in the appropriate Sundstrand service bulletin (see Table 2). Re-identify the torque tubes as indicated in the service bulletins.

Marking the service bulletin number on the rod with indelible ink will satisfy this requirement; or,

(ii) Replace the particular torque tube with a serviceable unit.