AoriiJ. 1998 

DATE ISSUED 

July 26. 2005 

Revision 1 

Subject: 

EFFECTIVITY: 

COMPLIANCE: 

Description: 

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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 - With in 1 0 hrs, then every 50 hours thereafter. 

Replacement of 2-2200-2 I Fitting: Every 850 hours. 

A recent incident involving failure of the attachment fitting of the lefthand horizontal stabilizer to the vertical tin has shown that a cause for 

initiation of a crack in the fitting can exist. The area in question is 

shown below. 

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REVO, Inc. 

SERVICE BULLETIN 8-78 Rl 

IN-SITU INSPECTION PROCEDURE: 

The fitting in the area of its attachment to the horizontal stabilizer rear beam may be 

initially inspected by raising the elevator and determining the distance between the fitting and the 

flanges of the beam doubler angles, and any contact of the 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. 

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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 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 fitting and visually inspect the top and bottom of the fittings 

using a magnifYing glass or horoscope. Pay 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 evident or suspected in this area, the fitting must be removed 

from the airplane (follow the removal instructions found in the APPENDIX of this bulletin) 

and inspected in accordance 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 ofthis bulletin). 

4. lfthe 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 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 of 850 hours. If the fitting has 850 hours or more, 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 structure. 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 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 drilling these (20) rivet holes in the field, 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 ofthe "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. 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 of S/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 of the stabilizer skin if necessary to keep 

at least 1/16" clearance between the skin and the fitting. Trimmed edges should be filed 

smooth with no sharp edges. 

8. Prior to reassembly, use brush A Iodine and primer on all bare metal exposed during the 

inspection and repair processes. 

9. Install the new 2-2200-21 fitting using AN4 70AD6 rivets. 

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REVO, Inc. 

SERVICE BULLETIN 8-78 Rl 

APPENDIX 

REMOVAL of HORIZONTAL TAIL HALVES: 

1. Disconnect the pushrod from the elevator horn inside 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 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 rear beam attach fitting. 

6. Remove the fitting from the stabilizer by carefully drilling out the AN4 70AD6 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. 

Elevator: up 26 deg. ± 1 deg. down 23 deg ± 1 deg. 

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. ± 1 deg. 

--End---

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