### REVO, Inc.

SERVICE BULLETIN B-78 R2

Page 2 of 4 IN-SITU INSPECTI ON PROCEDURE:

The fitting in the area of its attachment to the horizontal stabilizer rear beam may be initially inspected by raising the elevator and determini ng the distance between the fitting and the flanges of the beam doubler angles, and any contact of th e fitting with the skin. (See below). Both left and right stabilizer halves, top and bottom, must be checked for adequate clearance and any evidence of cracking where the inboard stabilizer beam channel and the stabilizer fitting meet.

1. Measure the clearance between the horizontal stabili zer skin and the fitting. If there is less than 1/16” clearance, trim the edge of the skin to provide at least 1/16” clearance.

2. Measure the gap between the horizontal stabilizer rear beam doubler angle and the fitting. The shank of a 5/32” drill bit may be used to check the gap.

3. If the gap is at least 5/32”: a) Clean the top and bottom of the fitti ng and visually inspect the top and bottom of the fittings using a magnifying glass or boroscope. Pa y extra attention to the front edge of the fitting in the area noted on the Figure on page 1 of this bulletin. Repeat this inspection every 50 hours until 850 hours of time is reached on the fitting.

b) If cracks, fretting or corrosion is eviden t or suspected in this area, the fitting must be removed from the airplane (follow the remova l instructions found in the APPENDIX of this bulletin) and inspected in accord ance with the “DETAILED INSPECTION and REPLACEMENT” section of this bulletin. If cracks, 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 of this bulletin).

4. If the gap is less than 5/32”, it will be necessary to remove the fitting in order to properly inspect it. Remove the fitting by following the removal instructions found in the APPENDIX of this bulletin and Inspect, and replace if necessary, in accordance with the “DETAILED INSPECTION

and REPLACEMENT” section of this bulletin. At the next 50 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 a nd replacement instructions in the APPENDIX and the DETAILED INSPECTION and REPLACEMENT sections).

### REVO, Inc.

SERVICE BULLETIN B-78 R2

Page 3 of 4 DETAILED INSPECTION and REPLACEMENT

1. 2200-14, 1-2200-14 and 2-2200-21 fittings have a lif e limit of 850 hours T.I.S. If a fitting has over 850 hrs TIS, or total time cannot be determ ined, it must be replaced; proceed to step 3.

2. With the fitting removed, inspect its forward face and edge for evidence of actual contact with the stabilizer beam or any adjacent struct ure. If contact has been present, the fitting will show signs of fretting or possibly the start of a crack. Removal of paint (by light sanding) will be necessary for this inspection. Inspect the area with a magnifying glass. Dye checking, per MIL-I-6866B or equivalent, is also recommended. If cracks, fretting or corrosion are present, the fitting must be replaced with a new 2-2200-21 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 drilling these (20) rivet holes in the fiel d, center the new fitting midway between the upper and lower beam and doubler flanges, with the centerline of the 3/8” bolt holes 15/16” (± 1/16”) inboard of the beam end. Check to assure that the fitting location meets the inspection requirements of items #1 and #2 of the “IN-SITU INSPECTION PROCEEDURE”

above.

5. Locate the rivet holes on the fitting by marking the forward face of the fitting through several

of the rivet holes in the stabilizer beam. Re move the fitting from the beam and mark the remaining rivet holes using the old fitting as a template. Check holes for minimum edge

distance of 5/16”.

6. Drill the (20) rivet holes with a #11 drill b it, using the old fitting as a drill template.

7. Before installing any fitting, trim the inboard edge of the stabilizer skin if necessary to keep

at least 1/16” clearance between the skin a nd the fitting. Trimmed edges should be filed smooth with no sharp edges.

8. Prior to reassembly, use brush Alodine and primer on all bare metal exposed during the inspection and repair processes.

9. Install the new 2-2200-21 fitting using AN470AD6 rivets.

### REVO, Inc.

SERVICE BULLETIN B-78 R2

Page 4 of 4 APPENDIX

REMOVAL and REINSTALLATION of HORIZONTAL TAIL HALVES:

1. Disconnect the pushrod from the elevator horn insi de the vertical tail. Allow the pushrod to lower out of the way.

2. Disconnect the trim surface torque tubes near the inboard end of the horizontal tail.

3. Unbolt the elevator from the elevator horn 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 rear beam attach fitting.

6. Remove the fitting from the stabilizer by car efully drilling out the AN470AD6 rivets.

7. Repeat the procedures 2 through 6 for the other stabilizer half if necessary.

8. After installing a new or corrected fitting onto the stabilizer rear beam, reverse the above procedure for reinstallation of the 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. Check travels and operation of elevator, trim surfaces, and rudder.

MODELS>

SURFACE Colonial

C-1 Colonial

C-2 Lake LA4, LA4A, LA4P, LA4-200
Elevator UP 18.5° 26° ±1° 26° ±1....°

Elevator DOWN 20°... 23° ±1° 23° ±1°....

Trim Tab UP -- -- 36° +2°/-1°

Trim Tab DOWN -- -- 24° +2°/-1° Rudder Left & Right 25° ±1° 25° ±1° 25° ±1....°

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