Airworthiness Directives for Mooney M20A

7. Remove the vertical fin. 8. Remove the tail truss assembly. Inspect the bolts and bushings for rust, corrosion, and elongated bolt holes. Inspect the wood for evidence of discoloration and deterioration. 9. Inspect the empennage attach fittings and bolts for wear and elongated bolt holes. C. Mandatory at the initial inspection. 1. Accomplish all inspection requirements noted in above Item II-B. 2. Remove the rudder and elevator control surfaces. 3. Inspect the rudder and elevator hinge fittings. 4. Inspect the bolts and bushings for evidence or rust or corrosion. Inspect the wood for discoloration and deterioration. (Refer to Figures 2 and 3.) 5. Check the ADF Antenna on aircraft equipped with and ADF for the following: a. 8 lbs. maximum tension on the antenna with one inch extension of the antenna spring with aircraft trimmed full nose up. b. 30 lbs. maximum tension on the antenna with aircraft trimmed full nose down. 261 MOONEY SERVICE BULLETIN M20-170A 6. Comply with Service Bulletin No. 20-62. D. GENERAL INSPECTION REQUIREMENTS AND REWORK RECOMMENDATIONS Applicable on the 90, 180, and initial inspection. 1. Carefully inspect all the skin attach areas (refer- ence Figures 2 and 3) for separation of glue joints by gently flexing adjacent parts or by tapping the joints with a small plastic mallet or hammer while listening for variations or changes in the sounds emitted. Rework all separated glue joints before further flight. 2. Remove the fabric from all suspect areas and inspect the wood for discoloration and deterioration. 3. Discoloration penetrating into the wood grain is considered evidence of wood deterioration. Sand all discolored areas to determine the depth of penetration into the wood grain. Repair all stain- ed and/or deteriorated wood before further flight. 4. Finish all the repaired or replaced wood with at least two coats of sealer or spar varnish on the interior surfaces. Do not allow sealer to contact the joint surfaces which are to be glued, as the gule will not adhere to the sealer. Exterior sur- faces where fabric will contact should be coated with dope-proof spar varnish or sealer. Coat the exposed end-grain in drain and vent holes with spar varnish or sealer and apply a final coat of aluminized spar varnish. 5. Apply fabric patches to all the areas where fabric has been removed for inspection of the wood. Allow the patch to overlap existing fabric at least two inches. Apply fabric patches over all the exposed wood surfaces including areas under fit- tings, etc. Do not cover the vertical fin spar stub- end which attaches to the horizontal stabilizer. 6. Refinish patched areas to match the existing finish. 7. Add a piece of water-proof tape on the right and left side of the horizontal stabilizer as shown in figure 4. 262 INSTRUCTIONS: PART III: MOONEY SERVICE BULLETIN M20-170A 8. Accomplish any repairs required in the wood empennage in accordance with FAA AC 43. 13-1 as required by FAR Part 43. INSPECTION OF WOOD WINGS Mandatory at the initial inspection unless already accomplished and at each annual inspection thereafter if conditions and environment do not warrant a m. re frequent inspection as noted: 1. Remove the wing to fuselage fairing and fillets. 2. Remove all the wing and center section access doors and panels. (Refer to Figure 5.) 3. Remove the sealing tape at the wing-fuselage joint and inspect the areas around the fittings for evi- dence of deterioration or joint separation. 4. Remove the rear seat and auxiliary fuel tank for access to the wing center section. 5. Remove the wing flaps and ailerons. Inspect the bolts, bearings and bushings for evidence of rust, corrosion and wear. 6. Check condition of the wing flap and aileron hinge fitting attach bolts and bushings. (Refer to Figure 6.) 7. Inspect the wood end-grain surrounding bolt holes for evidence of rust, discoloration, deterioration and evidence of moisture accumulation at the trail- ing edges of the wings. 8. Comply with Service Bulletins No. 20-29 and 20-67. 9. Inspect and clean all the drain holes in the lower wing skins. (Minimum 90 day inspection recom- mended.) 10. Inspect the fuel scupper areas for sealant condition between the scupper boxes and wing structure. General inspection requirements and rework recom- mendations. a. Carefully inspect all the skin attach areas for se ation of glue joints by gently flexing the adjace™ parts or by tapping the joints with a small plast 263 INSTRUCTIONS MOONEY SERVICE BULLETIN M20-170A mallet or hammer while listening for variations or changes in the sounds emitted. Rework all separated glue joints before further flight (reference Figure 6). b. Remove the fabric from all suspect areas and inspect the wood for discoloration and deterioration. c. Discoloration penetrating into the wood grain is con- sidered evidence of wood deterioration. Sand all the discolored areas to determine the depth of penetration into the wood grain. Repair all the stained and/or deteriorated wood before further flight. d. Finish all the repaired or replaced wood with at least two coats of sealer or spar varnish. The exterior surfaces of wood should be coated with dope-proof sealer or spar varnish. Coat the exposed end-grain in vent and drain holes with sealer or spar varnish and apply a final coat of aluminized spar varnish. e. Apply fabric patches to all areas where fabric has been removed for inspection of the wood. Allow patches to overlap the existing fabric at least two inches. Apply the fabric patches under the wing flap and aileron hinge fittings where the wood is exposed by cutouts in the existing fabric. f. Apply a coat of aluminized sealer or spar varnish to the wheel well area and wing center section as required, in accordance with Service Bulletin M20-67. g. Any repairs required in the wood wing must be accom- plished in accordance with FAA AC 43. 13-1 as required by FAR Part 43. PART IV: REPLACEMENT OF THE WOOD EMPENNAGE WITH AN ALL-METAL EMPENNAGE Replacement of the wood empennage with an all-metal empennage relieves the owner or operator from the rework and inspection requirements applicable to the wood empen- nage. Instructions and a kit enabling the replacement of the wood empennage assembly with an all-metal empennage assembly is supplied with Service Bulletin Kit 20-170-1. INQUIRIES CONCERNING THIS MODIFICATION OF M20 AND M20A AIRCRAFT SHOULD BE ADDRESSED TO MOONEY CORPORATION, CUSTOMER SERVICE DE PART- MENT, BOX 72, KERRVILLE, TEXAS 78028 264 COMPLIANCE NOTIFICATION: MOONEY SERVICE BULLETIN M20-170A To comply fully with this bulletin, complete and mail a Service Bulletin Compliance Card upon completion of inspection requirement, or installation of Service Bulletin M20-170-1 metal empennage kit. SERVICE BULLETIN KITS: A limited number of wood wing aircraft spare parts are available at Mooney Corporation, Spare Parts Depart- ment. No wood wing or empennage parts will be built by Mooney Corporation in the future. Service Bulletin M20-67 Kits are no longer available. Guidance as to materials acceptable for local manufacture of wood parts in accordance with FAA AC 43. 13-1 is contained in Service Bulletin M20-67. SERVICE BULLETIN M20-170-1 KIT: METAL EMPENNAGE KIT This kit is available to each M20/20A owner at $860 00 plus tax F.O.B. Kerrville, Texas. These kits will shipped only on instructions from registered M20/20A owners after "N" number, S/N verification. This is a special quantity production kit price establih- ed as non profit support for affected Mooney owners. Price is subject to change or withdrawal without prior notice and in no case will exceed one year from date of this bulletin. This offer is not intended to alter com- pany policy or set a precedent for future claims. Service Bulletin M20-170-1 metal empennage kit may be ordered directly from the factory (Phone 512-257- 4043). SERVICE BULLETIN M20-170-2 KIT: Repair Parts - This kit may be purchased through your local Mooney dealer or distributor. M20-170-15 (2) Straps (3) Bushings 265 914022-5 AN3-13A (2) Bolts AN3-14A (1) Bolt AN365-1032 (3) Nuts AN960-10 (6) Washers .250 Drill Dia, .254 1 1/2" Diameter Typical 14.75- (Ref.) 4.87 (Ref.)- L. H. Skin 38 to of Strap 4.75 3.00 L. H. Skin R. H. Skin 4.75 75k 4.75 2.25 holes through to match strap and add. 028 W.T. 1, O D. Zinc 10 Chromated bushings 4130 st. Cond N .859' Long or may use Mooney Reinforcing 14022-5 (3) Bushings Strap (Each Side) Attach With Bolts - AN3-13A (2) AN3-14A (1) AN960-10 AN365-1032 (6) Washers (3) Nuts Forward Face of Spar Aft Face of Spar Joggle Down .058 3.5 Detail A Strap one each side A 0.5 1.5 Typical .190 Diameter 194 (3 plcs) Zinc Chromate & Paint Strap 063 sht 4130 Cond N (or may use Mooney 20-170-15 straps.) Note: Glue joints are found wherever the wood contacts the internal structure e.g.: spar, rib, stringer, etc. FIG. 1 EMPENNAGE INSTALLATION Add access holes 1.5 inches diameter (smooth all edges) close holes using 5.5 inch diameter doped patches. Install reinforcing straps (P/N 20-170-15) or its equival picking up top cluster fitting attach bolt. (See Detail A use bolt sizes noted above) Install the bushings (P/N 914022 5) by first saturating the holes with spar varnish 266 Section A-A: (Typ. on access holes on horizontal stab.) Add Grommet at Lowest Point 1 1/2" Diameter Typical 5.25 5.25 -Fabric Patch 4.0 9.875 Plywood 4.75 A- 4.25 5.38 4.0 9.875 4.25 5.38 ון Elevator Hinge Detail 4.75 Forward Face of Horizontal Stabilizer FIG. 2 STABILIZER BOTTOM VIEW Add access holes 1.5 inches diameter in bottom skins as shown. (smooth all edges.) Close holes using 5.5 inch Dia. doped patches. Also add grommets to fabric patches approximately as shown. Note: Glue joints are found wherever the wood contacts the internal structure e.g.: spar, rib, stringer, etc. 267 Rudder Hinge Detail Hinges Front Face of Spar Inspect these two spar areas for any wood and/or glue joint deterioration including stain. FIG. 3 FIN ASSEMBLY Note: Glue joints are found wherever the wood skin contacts the internal structure e.g.: spar, rib, stringer, etc. 268 о Tail Truss Fin Add waterproof tape over cutout on op and down on front face. 0 FIG. 4 269 Stabilizer Fairings 0 0 0 FIG.5 ACCESS DOORS & PANELS Fairings 0 Stinger Assy 270 Under Wing Fairing 1 Flap Hinges Aileron Hinges FIG. 6 WING STRUCTURE BOTTOM VIEW Note: Glue joints are found wherever the wood contacts the internal structure e.g.: spar, rib, stringer, etc. 271 MOONEY SERVICE BULLETIN 20-170A Vertical Stabilizer Main Spar Crack Bottom Fin Rib Vertical Stabilizer Mart Spar 20-170A FIGURE 7. $272 Wood Discoloration Bottom Fin Rib