AoriiJ. 1998 DATE ISSUED July 26. 2005

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### Subject: EFFECTIVITY: COMPLIANCE: Description:



## t t REVO, Inc. SERVICE BULLETIN 8-78 Rl TECHNICAL ASPECTS OF THIS SERVICE BULLETIN ARE FAA APPROVED

# ~rr JUL 2 

### 8 2005 Horizontal Tail Attachment Fittiggs All Colonial C-2; Lake LA-4 & 

### LA-4-200 Models In-Situ Inspection

- Within 1 0 hrs, then every 50 hours thereafter. Replacement of2-2200-2 I Fitting: Every 850 hours. 

### A recent incident involving failure ofthe attachmentfitting ofthe lefthand horizontal stabilizerto the vertical tin has shown thata cause for initiation ofa crackin the fitting can exist. The areain question is 

### shown below. 

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### REVO, Inc. SERVICE BULLETIN 8-78 Rl IN-SITU INSPECTION PROCEDURE: The fitting in the area ofits attachment to the horizontal stabilizer rear beam may 

### be initially inspected by raisingthe elevator and determiningthe distance between the fitting and the flanges ofthe beam doubler angles, and any contact ofthe fitting with the skin. (See below). Both left and right stabilizer halves, top and bottom, must be checked for adequate clearance and any evidence ofcracking where the inboard stabilizer beam channel and the stabilizer fitting meet. 

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I. Measure the clearance between the horizontal stabilizer skin and the fitting. Ifthere is less than l/16"clearance, trim the edge ofthe skin to provide at least l/16" clearance. 2. Measure the gap between thehorizontal stabilizer rearbeam doubler angle and the fitting. The shank ofa 5/32" drill bit may be used to check the gap. 3. Ifthe gap is at least 5/32": a) Clean the top and bottom ofthe fitting and visually inspect the top and bottom ofthe fittings using a magnifYing glass or horoscope. Pay extra attention to the front edge ofthe fitting in the area noted on the Figure on page 1ofthis bulletin. Repeat this inspection every 50 hours until 850 hours oftime is reached on the fitting. b) Ifcracks, fretting or corrosion is evident orsuspected in this area, the fitting must be removed from the airplane (follow the removal instructions found in the APPENDIX ofthis bulletin) and inspected in accordance with the "DETAILED INSPECTION and REPLACEMENT'' section of this bulletin. Ifcracks, fretting or corrosion are present, the fitting must be replaced with a new fitting (follow the replacement instructions in the "DETAILED INSPECTION and REPLACEMENT" section ofthis bulletin). 4. lfthe gap is less than 5/32", it will be necessary to remove the fitting in orderto properly inspect it. Remove the fitting by following the removal instructions found in the APPENDIX ofthis bulletin and Inspect, and replace ifnecessary, in accordance with the "DETAILEDINSPECTION and REPLACEMENT" section ofthis bulletin. At the next SO hour inspection the inspections in Item 3 above may be followed. 5. When the part reaches 850 hours time in service the part must be removed from the airplane and replaced with a new fitting (follow the removal and replacement instructions in the APPENDIX and the DETAILED INSPECTION and REPLACEMENT sections).

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### REVO, Inc. SERVICE BULLETIN B-78 Rl DETAILED INSPECTION and REPLACEMENT l. 2-2200-21 fittings have a life limit of850 hours. Ifthe fitting has 850 hours ormore, proceed to step 3. 2. With the fitting removed, inspect its forward face and edge for evidence ofactual contact with the stabilizer beam orany adjacent structure. Ifcontact has been present, the fitting will show signs offretting or possibly the start ofa crack. Removal ofpaint (by light sanding) will be necessary for this inspection. Inspect the area with a magnifying glass. Dye checking, per MIL-I-6866B orequivalent, is also recommended. If

### cracks, fretting orcorrosion are present,the fitting must be 

### replaced with a new l-2200-21 fitting. 3. New fittings may come with or without the (20) 0.191" rivet holes. This is to allow the holes to be drilled in the field for improved alignment and fit. 4. Before drillingthese (20) rivet holes in the field, centerthe new fitting midway between the upper and lower beam and doubler flanges, with the centerline ofthe 3/8" boltholes 15/16" (± 1/16") inboard ofthe beam end. Checkto assure thatthe fitting location meets the inspection requirements ofitems #1 and #2 ofthe "IN-SITU INSPECTION PROCEEDURE" above. 5. Locate the rivet holes on the fitting by marking the forward face ofthe fitting through several ofthe rivet holes in the stabilizer beam. Remove the fitting from the beam and mark the remaining rivet holes using the old fitting as a template. Check holes for minimum edge distance ofS/16". 6. Drill the (20) rivet holes with a#II drill bit, using the old fitting as a drill template. 7. Before installing any fitting, trim the inboard edge ofthe stabilizer skin ifnecessary to keep at least 1/16" clearance between the skin and the fitting. Trimmed edges should be filed smooth with no sharp edges. 8. Priorto reassembly, use brush AIodine and primer on all bare metal exposed during the inspection and repair processes. 9. Install the new 2-2200-21 fitting using AN470AD6 rivets.

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### REVO, Inc. 

### SERVICE BULLETIN 8-78Rl
APPENDIX
REMOVAL ofHORIZONTALTAIL HALVES: 1. Disconnectthe pushrod from the elevator horn inside the vertical tail. Allow the pushrod to lower outofthe way. 2. Disconnectthe trim surface torque tubes nearthe inboard end ofthe horizontal tail. 3. Unboltthe elevatorfrom the elevator hom welded assembly. 4. Remove the elevator from the stabilizer by pulling the hinge pin. 5. With the horizontal tail supported, remove the AN4 bolt from the forward beam attach point, and remove the two AN6 bolts from the rearbeam attach fitting. 6. Remove the fitting from the stabilizer by carefully drilling outthe AN470AD6 rivets. 7. Repeat the procedures 2 through 6 for the other stabilizerhalfifnecessary. 8. After installing a new orcorrected fitting onto the stabilizerrearbeam, reverse the above procedure for reinstallation ofthe horizontal tail. (Existing bolts and hinges in good condition may be reused.) 9. Install all seals and access covers. (Existing parts may be re-used.) 

### 10. Checktravels and operation ofelevator, trim surfaces, and rudder. Elevator: up 26 deg. ± 1deg. down 23 deg ± 1deg. Trim Surfaces: up 36 deg. +2 deg. -1 deg down 24 deg. + 2 deg. -1 deg. Rudder: left 25 deg. ± I deg. Right 25 deg. ± 1deg. --End---

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