H&S Propeller Shop, Inc.
FAA Certified Repair Station # MQ5R050N
info@hspropeller.com

c. Minor Repairs of Aluminum Blades. Limited minor repairs may be made on propellers by appropriately rated maintenance technicians either on the aircraft or when the propeller is removed. Minor dents, cuts, scars, scratches, and nicks may be removed providing their removal does not weaken the blade, substantially change weight or balance, or otherwise impair its performance. The following paragraphs give guidance on the methods for accomplishing minor repairs. Before attempting to repair a propeller blade, determine whether the propeller manufacturer has published damage limits that govern repair procedures applicable to that part. Do not attempt a repair without knowing exactly what minor repairs, if any, are permissible. For example, straightening or reforming a blade is not considered a minor repair. Manufactures’ service documents and AC 43.13-1, current edition, provide additional repair instruction.

(1) Tools Required to Complete Minor Metal Blade Repairs Are:

(a) Fine-cut round and flat files.

(b) Ten-power loupe or magnifying glass.

(c) Emery cloth numbers 240, 320, and 600.

(d) Crocus cloth.

(2) Leading or Trailing Edge Damage. Refer to the propeller manufacturer’s maintenance documents for instructions on how to repair this damage. However, if the manufacturer did not publish this information, the following repairs can be made. For nicks, dents, pits, and cuts in the leading or trailing edges of blades, ensure that the bottom of the damage is removed first by rounding out and fairing in the repair only slightly deeper than the damage. Initial removal of material should be done using a fine cut file. All traces of file marks in the repaired area should be removed with number 240 emery cloth followed by polishing with number 320 emery cloth, then finished with crocus cloth or 600 grit emery cloth, and then visually inspected. An individual edge repair should not exceed a depth of 3/16-inch. The depth of repair should be greater than the depth of damage as given in Table 2-1. When repaired areas do not overlap, more than one repair may be accomplished. The repair length should be 10 times longer than the depth of the repair as shown in Figure 2-5, Techniques for Blade Repair. Refer to manufacturer’s instructions for repairs aft of the leading edge sections of the blade. For damage exceeding depths shown in Table 2-1, use the specific propeller manufacturer’s repair manual limits.

(3) Blade Face Surface Damage. Refer to the propeller manufacturer’s maintenance documents for instructions on how to repair this damage. However, if the manufacturer did not publish this information, the following repairs can be made. For gouges, cuts, and small dents on blade faces, ensure that the bottom of the damage is removed first by rounding out and fairing in the repair to form a saucer-shaped depression only slightly deeper than the damage. The initial repair should be accomplished by filing with a fine cut file parallel to the damage and finishing with 240 and 320 emery abrasive cloth, as in the manner of damage removal from blade-leading edges. Final polishing of the repair should be done with crocus cloth or 600 grit emery cloth. An individual repair should not exceed 1/16-inch in depth and the surface radius of curvature of the repair must not be less than 3/8-inch. Repair width should be 30 times the repair depth as shown in Figure 2-5. More than one repair is permitted when repair areas do not overlap an identical blade radius.

(4) Blade Tip Damage. Refer to the propeller manufacturer’s maintenance documents for instructions on how to repair this damage. However, if the manufacturer did not publish this information, the following repairs can be made. For nicks, dents, pits, and cuts in the tip of blades, repair in accordance with the procedures used for leading and trailing edge repair. Any removal of the blade tip material that reduces the blade radius below the minimum specified for the propeller manufacturer’s model designation and specific installation criteria is not permitted.

(5) Cracks. A crack in a blade may be discovered during the process of repair. Cracks found on a propeller CANNOT be repaired. The presence of a crack indicates that blade failure is virtually certain at any time. Cracks on the leading and trailing edges are especially prone to propagation. Blend outs or repairs should NEVER be attempted on these cracks. Propellers with cracks are unairworthy and MUST be removed from service and clearly identified as unairworthy.

(6) Inspection. Refer to the propeller manufacturer’s maintenance documents for instructions on how to repair this damage. However, if the manufacturer did not publish this information, the following inspection can be performed. Prior to return to service after minor repairs, the reworked area should be inspected with a minimum 10x power lens to ensure that any sharp notches at the bottom of the damage have been removed.