SERVICE LETTER NUMBER 136: 3000/3450 NOSE BOX - FINGER TAB INSTALLATION

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WIPLINE FLOATS • SKIS • MODIFICATIONS • AIRCRAFT SALES SERVICE LETTER 136 AVIONICS • INTERIOR • MAINTENANCE • PAINT REFINISHING PAGE 1 of 5 REV: B 1700 Henry Ave – Fleming Field (KSGS), South St. Paul, MN 55075 Ph: 651.451.1205 Fax: 651.457.7858 www.wipaire.com SERVICE LETTER NUMBER 136 TITLE: 3000/3450 NOSE BOX - FINGER TAB INSTALLATION BY: J. Sortor AIRCRAFT MAKE/MODEL(S): Cessna: 180, 182, 185,206 Maule: M-6-235; M-7-235; M-7-235B; M-7-235C; M-7-260; M-7-260C; M-7-420A; M-7-4Z0AC; MT-7-235; MT-7-260; MX-7-235 FLOAT MODEL(S): 3000 Amphibian 3450 Amphibian NOTE(S): OPTIONAL COMPLAINCE S/L P/N 1005835 ECO--23245 APP: D.Garrett DATE: 7/8/2013 REV: B FAA APPROVAL HAS BEEN OBTAINED FOR TECHNICAL DATA IN THIS PUBLICATION THAT AFFECTS STC OR TSO DESIGN COMPLIANCE EFFECTIVITY: This service letter applies to all Wipline model 3000 S/N 30231 and prior and 3450 S/N 34272 and prior amphibious floats, as installed on the following aircraft Cessna 180/185 on Wipline 3000 amphibian floats per STC SA01320CH Cessna 182 on Wipline 3000 amphibian floats per STC SA001156CH Maule series on Wipline 3000 amphibian floats per STC SA01412CH Cessna 206 on Wipline 3450 amphibian floats per STC SA01185CH SERVICE LETTER P/N: 1005835 COMPLIANCE: Service letter compliance is optional. BACKGROUND: The lower hole in nose track component (21A07349-003 & -004) and or nose box (30A07323-002) can oblong causing the nose track/nose box joint to become loose. This loosening of the nose track to the nose box causes the nose bulkhead to flex; in some cases this causes the nose bulkhead to develop cracks due to excessive deflection over time. It is thought that this problem is exacerbated by grass field operations that would cause the nose gear to work back and forth repeatedly in any takeoff or landing. It is also thought that the sudden jolt of aircraft towing may play a role in deforming the lower hole. WIPLINE FLOATS • SKIS • MODIFICATIONS • AIRCRAFT SALES SERVICE LETTER 136 AVIONICS • INTERIOR • MAINTENANCE • PAINT REFINISHING PAGE 2 of 5 REV: B WARRANTY INFORMATION: This service letter includes warranty on repair parts, but does not include warranty on existing parts. APPROXIMATE SHOP HOURS: The functions outlined by this service bulletin will take approximately 8-10 hrs. to accomplish. TECHNICAL DATA AND INSTRUCTIONS: 1. Inspect nose track for loose connection. This can be done by jacking with a pallet jack under the keel near the bow with the gear in the down position. Once the weight is off of the nose tire grab firmly at the nose track, push fore and aft. If there is play in the joint and you can see the nose bulkhead flexing then the service kit should be installed. 2. If nose track is loose, complete the remaining steps: 3. Remove nose box assembly and nose tracks from float. Lower attachment holes oblong and loosen the nose box/nose track attachment. WIPLINE FLOATS • SKIS • MODIFICATIONS • AIRCRAFT SALES SERVICE LETTER 136 AVIONICS • INTERIOR • MAINTENANCE • PAINT REFINISHING PAGE 3 of 5 REV: B 4. Scrape sealant away and inspect nose bulkhead for cracks, especially near lower bolt attachment. If the bulkhead is cracked it must be replaced (PN 30A01155-029). 5. Unbolt nose track PN 21A07349-003 & -004 (Item 4 below) from nose box PN 30A07323-002 (Item 1 below) and inspect mating holes. 6. If holes are out of round (which is very likely if you can see flexing of the nose bulkhead in step 1) it is acceptable to upsize lower mating nose box and nose track holes (Item 9 above) from ¼” to 5/16”. Picture of forward bulkhead crack WIPLINE FLOATS • SKIS • MODIFICATIONS • AIRCRAFT SALES SERVICE LETTER 136 AVIONICS • INTERIOR • MAINTENANCE • PAINT REFINISHING PAGE 4 of 5 REV: B 7. Finger Patch Installation. To install the finger patch proceed with the following steps: 8. Fit Finger Patch PN 1005833 to Nose Track PNs 21A07349-003 & -004 by placing into bolt recess and ensuring that the patch sits flat to bolt hole face. This part should be a tight fit, remove any material on finger patch that keeps it from sitting flat. 9. Install bolt through finger patch (1005833), Nose Track (21A07349-003), and Nose Box (30A07323-002). Tighten nut to verify a good fit. Note: if the lower mating hole was opened to 5/16” the hole in the finger patch must also be opened up to 5/16” 10. Once each finger patch is fit, unbolt nose track and finger patch from nose box and fully degrease nose track and finger patch. This step is important because adhesive will be used to permanently bond the finger patch to the nose track in the next step. 11. Once finger patch and nose track have been thoroughly cleaned, use an adhesive to bond the finger patch (1005833) to the nose track (21A07349-003). Acceptable adhesives include: a. Aviation Grade PR-1422-B-1/2 (Polysulfide fuel tank sealer - PRC) or equivalent WIPLINE FLOATS • SKIS • MODIFICATIONS • AIRCRAFT SALES SERVICE LETTER 136 AVIONICS • INTERIOR • MAINTENANCE • PAINT REFINISHING PAGE 5 of 5 REV: B b. 3M DP-190 (Toughened Epoxy) or similar structural adhesive 12. Once adhesive is applied to entire mating surface install a bolt through the mating hole to ensure alignment and secure bolt to apply pressure to glue joint while curing. The intention is to glue the finger patch (1005833) to the nose tracks (21A07349-003/-004) first and then reassemble with the nose box, however it is acceptable to assemble entire modification wet with PRC instead of gluing finger patch to nose track first. This wet assembly is not recommended if using a structural epoxy as it will be very difficult to disassemble in the future. 13. Once the finger patches are glued to the nose tracks, reinstall nose tracks to nose box and transfer the two additional holes (2 each side) from the finger patch to the nose box. If the nose box/nose track mating hole was opened to 5/16” it is acceptable to open remaining finger patch and spacer (1005834) holes to 5/16” to keep mating hardware consistent.