Commonwealth legislation

AD/DC3/13 - Flap Adjustment

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legislative instrument

Plain English Summary

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This Airworthiness Directive requires all Douglas DC‑3 aeroplanes to have their flap push‑pull linkages adjusted to specific measurements and clearances and for maintenance manuals to be amended. It replaces an ambiguous service bulletin by prescribing exact rod lengths, turnbuckle settings, flap angle (45° ±2°) and pad clearances to reduce the risk of push‑pull tube failures. Operators and maintenance organisations must perform the hands‑on adjustments and bear the associated inspection, adjustment and documentation costs.

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AD/DC3/13 - Flap Adjustment

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Douglas DC3 Series Aeroplanes

AD/DC3/13 Flap Adjustment NK

Applicability: All models.

Requirement: 1. Douglas SB No. 204 supplemented by Douglas Service for May 1947, page 18, leaves much to individual interpretation and consequently there is a possibility of maladjustment which may lead to flap push-pull tube failures. Flaps are to be adjusted in accordance with the procedure prescribed in para. 2 below.

2. Adjust the flaps in accordance with the following:

(a) Fully bottom jack in down position.

(b) Set the inboard rod adjustment to 7/8 inch between the tube end and the trunnion hexagon.

(c) Set the outboard adjustment to 1 1/2 inches between the tube ends.

(d) Place a 45 degree template between the underside of the flap and wing and set each turnbuckle (turnbuckles should be approximately 75 degree to push-pull tubes).

(e) Slowly raise flaps on handpump, checking the relative timing between the inboard and outboard flaps.

(f) Adjust the flaps to the same timing.

(g) With the actuating jack fully bottomed in the up position, adjust each turnbuckle to give a clearance of the flap from the felt pads of .05 inch. This clearance may be obtained by using a piece of 18 gauge metal sheet as a feeler gauge, first shaping the sheet to fit into position.

(h) Tighten each turnbuckle one turn (this raises the trailing edge of the flap .09 inch, giving a pad compression of 04 inch).

(i) Readjust with different setting of push-pull tubes if flap angle at full deflection is not 45 degrees + 2 degrees.

3. It should be noted that the flap operating linkage is such that with the flaps down slight slackness will be apparent at the trailing edge. This is normal and the turnbuckles must not be adjusted to eliminate this slackness.

4. Amend Maintenance Manuals to comply with this directive. OR ANO 105.1.6.1.5.14.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.

1 AD/DC3/13 - Flap Adjustment

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

Douglas DC3 Series Aeroplanes

AD/DC3/13 Flap Adjustment NK

Applicability: All models.

2. Adjust the flaps in accordance with the following:

(a) Fully bottom jack in down position.

(b) Set the inboard rod adjustment to 7/8 inch between the tube end and the trunnion hexagon.

(c) Set the outboard adjustment to 1 1/2 inches between the tube ends.

(d) Place a 45 degree template between the underside of the flap and wing and set each turnbuckle (turnbuckles should be approximately 75 degree to push-pull tubes).

(e) Slowly raise flaps on handpump, checking the relative timing between the inboard and outboard flaps.

(f) Adjust the flaps to the same timing.

(g) With the actuating jack fully bottomed in the up position, adjust each turnbuckle to give a clearance of the flap from the felt pads of .05 inch. This clearance may be obtained by using a piece of 18 gauge metal sheet as a feeler gauge, first shaping the sheet to fit into position.

(h) Tighten each turnbuckle one turn (this raises the trailing edge of the flap .09 inch, giving a pad compression of 04 inch).

(i) Readjust with different setting of push-pull tubes if flap angle at full deflection is not 45 degrees + 2 degrees.

3. It should be noted that the flap operating linkage is such that with the flaps down slight slackness will be apparent at the trailing edge. This is normal and the turnbuckles must not be adjusted to eliminate this slackness.

4. Amend Maintenance Manuals to comply with this directive. OR ANO 105.1.6.1.5.14.