AN APPROPRIATE ENTRY SHOULD BE MADE IN THE AIRCRAFT LOGBOOK UPON ACCOMPLISHMENT
IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER MODEL AFFECTED: 407

SUBJECT: HORIZONTAL STABILIZER INSTALLATION 407

- 023

- 800

- ALL, IMPROVEMENT OF

HELICOPTERS AFFECTED: 407, Serial Number 53000 through 53339.

[Helicopters Serial Number 53340 and subsequent

will have the inte nt of this bulletin completed before delivery]

COMPLIANCE: At the option of the operator. However, BHT recommends that you do this bulletin at the next scheduled inspection.

DESCRIPTION:

Bell Helicopter has received reports of upper horizontal stabil izer attachment supports found cracked in service. All cracks were found during routine or scheduled maintenance in the same location of the left or right upper stabilizer supports 407

- 023

- 800

- 117 or /

- 118.

Investigation showed that gaps can exist betwee n the attachment flange of the stabilizer supports and the stabilizer upper or lower surfaces. To eliminate these gaps and reduce the loads affecting each stabilizer attachment supports, BHT has approved the installation of shims in the form of shimming c ompound (full length of each support attachment flange) and solid shim(s) riveted to the stabilizer upper surface. Once installed, the cured shimming compound and solid shim(s) will eliminate the risk of the stabilizer supports to crack in service.

This bulletin gives instructions to check for, measure and correct any gap(s) that can exist between each of the stabilizer attachment supports and the surface of the

stabilizer. No. 407

- 01

- 33

Date 08

- 29

- 01

Page 1 of 23 DATE

REV 

## TECHNICAL BULLETIN

A Subsidiary of Textron Inc.TB 407

- 01

- 33

Page 2 of 23

APPROVAL:

The engineering design aspects of this bulletin are Transport Canada approved.

MANPOWER:

Approximately 8.0 man

- hours are necessary to complete this bulletin. Man

- hours are

based on hands

- on time, and can vary with personnel and facilities available.

MATERIALS:

Required Material: The material that follows is necessary to complete this bulletin and can be procured through your Bell Helicopter Textron Supply Center.

Part Number Nomenclature Quantity

100

- 204

- 2 Identification plate 3

MS27039

- 1

- 05 Screw 32

Consumable Material: The material that follows is necessary to complete this bulletin, however this material is considered consumable (bench stock) material and may not need to be ordered depending on the operators consumable material stock levels. This material can be procured through your Bell Helicopter Textro n Supply Center.

Part Number Nomenclature Reference

EC2216 B/A TAN N/S Adhesive C

- 322 (Note 4)

299

- 947

- 100TY2CL2PT Adhesive C

- 317

MIL

- PRF

- 81733 Sealant C

- 392 (Note 1)

Acetone Acetone (per Q

- A

- 51) C

- 316 (Note 2)

MIL

- P

- 85582, TY1, CL2 Primer C

- 204 (Note 3)

MIL

- C

- 81706 1 GAL Chem Film C

- 100

P

- P

- 101 Aluminum Oxide Sandpaper C

- 423

299

- 947

- 110TY3CL1 2I Teflon tape (2 inch wide) C

- 460

PETROLATUM 16 OZ Petrolatum (Petrolatum Jelly) C

- 008

Notes:

1. Formerly MIL

- S

- 81733

2. As an alternative, use Methyl Ethy l Ketone ( C

- 309 )

3. As an alternative, use MIL

- P

- 23377

4. A quantity of 4 Oz. Minimum is needed to do the installation on one aircraft.TB 407

- 01

- 33 Page 3 of 23

SPECIAL TOOLS:

Not required

WEIGHT AND BALANCE:

The modification of the stabilizer installation as described in this bull etin has a negligible effect to the Weigh and Balance of the aircraft.

ELECTRICAL LOAD DATA:

Not affected

REFERENCES:

BHT

- 407

- MM

- 5 , Rev. 10, 16 February 2001

Chapter 53, Fuselage

BHT

- 407

- IPB , Rev 01, 09 February 2000

Chapter 53 , Fuselage

BHT

- 206

- SRM

- 1 , Rev. 1, 04 April 1995

BHT

- ALL

- SPM, Reissue, 20 August 1999

PUBLICATIONS AFFECTED:

BHT

- 407

- MM

- 5 , Rev. 10, 16 February 2001

Chapter 53, Fuselage

BHT

- 407

- IBP, Rev 01, 09 February 2000

Chapter 53 , Fuselage

PART 1: IMPROVED INSTALLATION OF HOR IZONTAL STABILIZER

1) Refer to Figure 1 . Remove the lower left and right stabilizer support assemblies (1, 2) from the tailboom (5) and the stabilizer (6) and examine for condition.TB 407

- 01

- 33

Page 4 of 23

- NOTE

It is not necessary to disassemble the lower support angles (14,15 ) from the closure plates (16,17).

2) Use a plastic scrapper to remove any cured sealant or debris from faying surfaces of each support (1, 2).

- NOTE

A thin strip of sealant installed at the factory covers the

stabilizer attachment inserts to create a dis similar metal barrier. This strip of sealant is not necessary and can be removed after you have done this bulletin.

3) Refer to the Maintenance Manual, chapter 53 , and remove the stabilizer (6) from the tailboom (5). Examine the stabilizer (6) for conditio n.

4) Use a plastic scrapper to remove the cured sealant strips covering each row of inserts, which serve to attach the stabilizer (6) to the tailboom (5).

5) Use a plastic scrapper to remove any cured sealant or debris from attachment flanges of upper stabil izer supports (3, 4) riveted to tailboom (5).

6) Refer to Figure 1 , View B

- B. Install the stabilizer (6) into the tailboom (5). Use four screws (10) at hole locations #2 and #8 to temporarily secure the stabilizer (6) to the upper left and right supports ( 3, 4). Do not tighten the screws at this

time.

- NOTE

The gap should be set using a feeler gauge and should be 0.003 inch (0.08 mm) at the minimum gap location.

7) Hand tighten each screw (10) at hole locations #2 and #8 on each side of the tailboom (5) un til you can run with slight restriction, a 0.003 inch (0.08 mm) feeler gage. Run the feeler gage between the stabilizer (6) and the horizontal flange of each support (3 and 4) along the full length and width of the attachment flange

forward of screw #8. This 0.003 inch (0.08 mm) minimum clearance along the flange of each support will make sure that there is no preload condition.

- NOTE

An “L

- shaped” riveted shim (18) (Ref. To Figure 1 , view B

- B, Detail C) may have been installed on the stabilizer (6) ne w from the factory or because of previous field accomplishmentTB 407

- 01

- 33 Page 5 of 23

of this procedure. If this “L

- shaped” shim (18) interferes with the shimming procedure below, remove shim (18). The

instructions that follow will determine if a new “L

- shaped”

shim is needed. If “L

- shaped” shim (18) is no longer needed, plug unused rivet holes in trailing edge of the stabilizer (6) with rivets MS20470AD3.

8) With the stabilizer (6) installed as per Step 6 and Step 7, measure gap between both upper supports (3, 4) and horizontal stabilizer (6) upper surface, aft of hole #8. Measure aft of screw at location #8 to the trailing edge of the stabilizer (6) and across full width of the attachment flange of upper support (3, 4).

a) If measured gap at the trailing edge area of the stabiliz er (6) exceeds 0.085 inch (2.16 mm), contact Product Support Engineering for procedural guidance at the following;

Bell Helicopter Textron

Product Support Engineering

Tel: 1

- 800

- 243

- 6407 (Continental USA and Canada)

Tel: 1

- 800

- 363

- 8023 (Continental USA)

T el: 1

- 800

- 361

- 9305 (within Canada)

Tel: 1

- 450

- 437

- 2862 (all other areas

- call collect)

Fax: 1

- 450

- 433

- 0272

Internet: pselight@bellhelicopter.textron.com

b) If measured gap in the trailing edge area o f the stabilizer (6) is less than 0.050 inch (1.27 mm), the gap will be shimmed later using “shimming compound” ( C

322 ). Go to Step 9.

c) If measured gap at the trailing edge area of the stabilizer (6) is between 0.050 inch (1.27 mm) and 0.085 inch (2.16 mm) maximum, remove the stabilizer (6) from the tailboom (5) and rework the trailing edge as follows;

i. Refer to Figure 1, View B

- B and Detail C. Fabricate a “L

- shaped” solid shim (18) using the appropriate thickness of 2024T3 Al Alloy material. Taper the

s him (18) as needed to fill the gaps measured earlier. The leg extending inboard must have a constant thickness equivalent to thickness of gap at inboard radius of upper support (3, 4), but no less than 0.015 inch. .

ii. Locate formed shim (18) in position o n stabilizer (6) and drill for installation of additional MS20470AD3 rivets (Qty 2 each) as indicated in Detail C. Maintain proper rivet edge distance of 2D and spacing of 4 D minimum.

iii. Transfer the existing #9 fastener hole (0.209 inch (5.30 mm) diamete r) from the stabilizer (6) to the shim (18).TB 407

- 01

- 33

Page 6 of 23

iv. Remove the shim (18) and deburr all holes. Break all sharp edges and

remove debris and loose material.

v. Prepare the upper surface of stabilizer (6) and the shim (18) in accordance with paragraphs 3

- 2

- 3 and 3

- 2

- 7 of the Structural Repair Manual ( BHT

- 206

- SRM

- 1 ). Bond and secure the shim in place on the stabilizer using adhesive ( C

- 317 ) and rivets MS20470AD3 (grip length to suit). Remove excess adhesive squeeze

- out and apply a pressure between 0.5 to 1.0 PSI

befor e you let cure at room temperature for 24 hours.

vi. Seal all the edges of the shim (18) with sealant ( C

- 392 ) and let cure.

9) Do Steps 6, 7 and 8 again.

10) Attach each lower support assemblies (1, 2) to the tailboom (5) using the screws (13). Tighten each scr ew . Do not install the screws common to the stabilizer

at this time.

11) Verify that you have acceptable gaps between the stabilizer (6) and the horizontal flange of the lower support angles 14, 15) as follows;

a) Run a 0.003 inch (0.08 mm) feeler gag e, between the stabilizer (6) and the horizontal flange of each lower support assembly (1, 2). The feeler gage should be run along the full length and width of the attachment flange. This 0.003 inch (0.08 mm) minimum clearance along the flange of each su pport will make sure that there is no pre

- load condition.

b) Gaps must not exceed 0.050 inch (1.27 mm) at any location.

c) If you cannot obtain a clearance between 0.003 inch (0.08 mm) and 0.050 inch (1.27 mm) do the following:

- NOTE

You can enlarge and slot the holes of the lower support assemblies (1, 2), common to the tailboom skin only. Slot the holes as necessary in the upward direction perpendicular to the tailboom (5) only as shown in Figure 1 Detail D.

i. Increase in the affected lower support asse mbly (1, 2), all the existing .214 inch (5.44 mm) diameter holes (qty. 18) that are common with the tailboom skin (5). Do not exceed a maximum diameter of .231 inch (5.87 mm). This will help to get clearance between the stabilizer (6) lower surface and t he flange of the affected lower support.TB 407

- 01

- 33 Page 7 of 23

ii. Install the reworked lower support assembly (1, 2) and do Step 11a and Step 11b. If you get a correct gap, go to Step 12.

iii. If more clearance is needed, slot all the holes (qty. 18) in the upward direction only, by an equal amount, not exceeding the 0.250

- inch (6.35 mm)

vertical dimension shown in Detail D

.

iv. Install the reworked lower support assembly (1, 2) and do Step 11a and Step 11b. If you get a correct gap, go to Step 12.

v. If you do not get a correct gap, repl ace the affected lower support (14, 15) in accordance with Part II of this bulletin (refer to 407 IPB for replacement part numbers) before you do Step 11a and 11b again.

12) Remove both lower support assemblies (1, 2) and the stabilizer (6) from tailboom (5).

13) Record the stabilizer (6) part number and serial number indicated on the identification plate located on the upper surface, near the trailing edge of the

stabilizer at BL 0.00.

CAUTION

DO NOT SOAK PARTS TO BE CLEANED WITH CLEANER (M.E.K., ACETONE, ET C.). DO NOT EXPOSE

BARE METAL.

14) Use a cloth moist with Acetone ( C

- 316 ) to clean the upper and lower surfaces of

the stabilizer.

15) Apply a strip of Teflon tape ( C

- 460 ) over surfaces of the stabilizer (6) mating with the horizontal flanges of the upper and l ower supports (1, 2, 3, 4) as follows;

a) The tape must be centered with each row of the stabilizer inserts.

b) The tape must be free of wrinkles or entrapped air bubbles after installation.

c) Do not puncture tape at any insert location.

16) Carefully abrade the p rimer coating on each horizontal flange of the upper supports (3,4) and each lower support assemblies (1, 2), including bend radius area. Use a cloth moist with Acetone ( C

- 316 ) to clean reworked areas.TB 407

- 01

- 33

Page 8 of 23

17) Put the stabilizer (6) back into position through ta ilboom (5). Do not attach the stabilizer to the upper supports (3, 4) at this time, but leave it resting with adequate protection on lower edge of tailboom skin cutouts.

- NOTE

A minimum quantity of 4 ounces (118 ml) is needed to do

this modification on

one aircraft. The pot life of the shimming compound ( C

- 322 ) is approximately 1 hour.

18) Mix an acceptable quantity of shimming compound ( C

- 322 ).

19) Apply a liberal amount of shimming compound ( C

- 322 ) to the horizontal flange of each upper support (3, 4). The amount of shimming compound must be sufficient so that the squeeze

- out, which will occur, will cover the inboard bend radius of each horizontal flange.

- NOTE

Do not over tighten the screws (10). During the curing process, the screws (10) will be used for alignment purpose only.

CAUTION

DO NOT PUT EXCESSIVE PETROLATUM ( C

- 008 ) ON THE SCREWS (10) BECAUSE THIS CAN CONTAMINATE THE SHIMMING COMPOUND ( C

- 322 ).

20) Apply a light layer of Petrolatum ( C

- 008 ) to four screws (10) and four washers (11).

- NOTE

A m inimum of two persons is needed to do the following Steps.

- NOTE

Puncture the Teflon tape ( C

- 460 ) on the stabilizer (6) only where indicated, using applicable screw (10).

21) Slowly lift the stabilizer (6) close to the upper supports (3, 4) and install the screws (10) and the washers (11), two per side, at the #2 and #8 hole locations. Use the screws (10) to make a hole in the tape ( C

- 460 ).TB 407

- 01

- 33 Page 9 of 23

22) Engage each screw (10) between two to three threads maximum into the stabilizer insert but do not tighten. The scr ew (10) through the Teflon tape ( C

460 ) creates a seal to prevent inserts contamination. Make sure that the surface of the stabilizer (6) does not contact the shimming compound ( C

- 322 ) at this time or it may cause voids. The four screws (10) will support the stabilizer (6) away from the wet compound.

23) Apply a liberal amount of shimming compound ( C

- 322 ) to horizontal flange of each lower supports assemblies (1, 2). The amount of shimming compound must be sufficient so that the squeeze

- out, which will occur, will cover the inboard bend radius of each horizontal flange.

- NOTE

Do not over tighten the screws (12). During the curing process, the screws (12) will be used for alignment purpose only.

CAUTION

DO NOT PUT EXCESSIVE PETROLATUM ON THE SCREWS (12) A

ND THE WASHERS (11) BECAUSE THIS CAN CONTAMINATE THE SHIMMING COMPOUND ( C

322 ).

24) Apply a light layer of Petrolatum ( C

- 008 ) to four screws (12) and four washers (11).

25) Install two screws (12) and two washers (11), through the #2 and #8 hole location

of each flange of the lower support assemblies (1, 2).

26) Slowly lift each lower support assembly (1, 2) to the lower surface of the stabilizer (6) but do not make contact at this time. Align each screw (12) with the mating insert of the stabilizer (6). Use each s crew (12) to make a hole in the tape ( C

- 460 ). Make sure that the compound ( C

- 322 ) on the flange of each support assembly (1, 2) does not contact the stabilizer (6) at this time or it may cause

voids.

27) Engage each screw (12) between two to three threads ma ximum into the stabilizer insert but do not tighten. The screw (12) through the Teflon tape ( C

460 ) creates a seal to prevent inserts contamination. The four screws (12) will not be tightened but will serve as alignment pins at this time.

28) Use each lowe r support assembly (1, 2) to raise and counteract the weight of stabilizer. Raise the stabilizer (6) until the holes in the closure plates (16, 17) areTB 407

- 01

- 33

Page 10 of 23

in line with the holes in the tailboom skins (7, 8). Install the screws (13) to secure the lower suppo rt assemblies (1, 2). Torque each screw (13) .

- Note

Do not attempt to remove shimming compound ( C

- 322 )

squeeze

- out at bend radius of upper supports (3, 4) or lower support assemblies (1, 2).

29) Remove unwanted shimming compound (C

- 322 ) at all screw holes.

30) Clean edges of flanges of upper and lower supports (1, 2, 3, 4) as follows;

a) Make sure that the wet compound does not go beyond the edges of the Teflon tape ( C

- 460 ), onto the stabilizer (6) surfaces.

b) Make sure that the wet compound ( C

- 322 ) from up per and lower supports (1, 2, 3, 4) do not mate together at the leading and trailing edge locations or it will bond parts with each other.

- NOTE

Accelerated cure can be achieved by using 150 Deg F (66 Deg C) for 2 hours.

31) Let the shimming compound ( C

- 3 22 ) to cure at room temperature for 16 hours

minimum.

32) After the adhesive has cured, delicately remove lower support assemblies (1, 2) and the stabilizer (6) from the tailboom (5). 33) Examine the cured shimming compound ( C

- 322 ) on horizontal flange of each

s upports (1, 2, 3, 4) for condition as follows;

a) The cured compound must cover the inboard bend radius and all mating

surfaces. b) Small pinholes or porosity are acceptable.

c) Small void areas no bigger than 0.15

- inch (3.81 mm) diameter and 1 inch (25.4 mm) apart or more are acceptable. If voids exist in excess of these limitations, remove cured compound ( C

- 322 ), clean the flange and do the shimming procedure again.

d) The compound must not exceed 0.050 inch (1.27 mm) thick at any location except in bend radi us area. If the maximum thickness is exceeded, replace lower support unit in accordance with Part II before you do Steps 14 through 33 again.TB 407

- 01

- 33 Page 11 of 23

CAUTION

IF A POWER DEVICE (EXAMPLE: ROTARY OR BELT SANDER) IS USED TO TRIM THE SHIMMING COMPOUND ( C

- 322 ), MAKE SURE YOU DO NOT DAMAGE THE BEND RADIUS OF THE SUPPORTS (1, 2, 3, 4).

34) Remove the cured shimming compound ( C

- 322 ) that is in excess at each bend radius and outboard edges of the supports (1, 2, 3, 4).

35) Clean all screw holes in the flange of each support (1, 2, 3, 4). Footprint of stabilizer inserts in shimming compound may be visible and can serve as a reference to clean the shimming compound ( C

- 322 ) in the flange of each support.

- NOTE

Do not prime the cured shimming compound ( C

- 322 ).

36) Refinish all bare metal surfaces on each support (1, 2, 3, 4) using primer ( C

- 204 ). Let primer dry.

37) Cover the cured shimming compound ( C

- 322 ) of each support (1, 2, 3, 4) with a strip of Teflon tape (C

- 460) . Trim tape to match the faying surface of each

horizontal flan

ge. Puncture the tape for each screw holes.

38) Remove the Teflon tapes ( C

- 460 ) from the stabilizer (6).

CAUTION

AFTER THE SHIMMING PROCEDURE IS DONE, THE STABILIZER ASSEMBLY (6), THE TAILBOOM ASSEMBLY (5) AND THE ATTACHMENT SUPPORTS (1, 2, 3, 4) ARE CONS IDERED A MATCHED SET. THE TAILBOOM ASSEMBLY (5), THE STABILIZER ASSEMBLY (6) AND/OR THE LOWER ATTACHMENT SUPPORT ASSEMBLIES (1,2) ARE NOT INTERCHANGEABLE BETWEEN AIRCRAFT, UNLESS

THIS SHIMMING PROCEDURE IS REPEATED.

39) Refer to Figure 2, Detail F . Use a pen and mark two identification plates (19) with the appropriate information as follows;

a) Mark the first line of each plate (19) to read: “ THIS PART IS MATCHED
SET TO”.TB 407

- 01

- 33

Page 12 of 23

b) Mark the second line to read: “ TAILBOOM P/N AND S/N REF”.

c) Mark the third and fourth li ne of each plate (19) to show the existing tailboom part number and serial number respectively

d) Mark the fifth line to read: “HORIZONTAL STABILIZER P/N AND S/N

REF”.

e) Mark the sixth and seventh line of each plate (19) to show the existing
horizontal stab ilizer part number and serial number respectively

.

f) Install the identification plates (19) on each support at location indicated by Figure 2, Detail E.

40) Refer to Figure 2, Detail G . Use a pen and mark one identification plate (19) with the appropriate info rmation as follows;

a) Mark the first line of the plate (19) to read: “ THIS PART IS MATCHED

TO”.

b) Mark the second line to read: “TAILBOOM P/N AND S/N REF”.

c) Mark the third and fourth line of the plate (19) to show the existing tailboom part number and ser ial number respectively.

d) Leave the fifth, the sixth and seventh lines of the plate (19)

unmarked.

e) Install plate (19) on upper surface of the stabilizer (6) at the

area shown in Figure 2, View H.

CAUTION

MAKE SURE THAT ALL SCREWS MS27039

- 1

- 05 USED

TO AT TACH THE STABILIZER (6) TO THE TAILBOOM (5)

ARE THE CORRECT AND IDENTICAL LENGTH AT ALL LOCATIONS. IF TOO LONG A SCREW IS USED, IT MAY
PUNCTURE AN INSERT AND THE INSERT WILL NEED

TO BE REPLACED.

- NOTE

Make sure that there is no debris inside the insert of the stabilizer (6).TB 407

- 01

- 33 Page 13 of 23

41) Before you install the stabilizer (6), install a screw (10) in each insert of the stabilizer (6). Tighten each screw (10) until they bottom out in the insert but do not exceed 25 inch/lbs of torque.

a) Measure the gap between the und erside of each screw head and the upper

surface of the insert.

b) A gap of less than 0.063 inch (1.60 mm) for each insert location is acceptable. This will make sure that a proper clamp

- up of the stabilizer (6) by each supports (1, 2, 3, 4) will be obtain ed. Go to Step 42.

c) A gap at any insert location in excess of 0.063 inch (1.60 mm) is not acceptable. Contact Product Support Engineering with details before you continue with the installation of the stabilizer (6).

42) Use the sequence that follows to perm anently install the stabilizer (6) to the tailboom (5);

a) Attach the stabilizer (6) loosely to each upper support (3, 4), using the screw (10) and the washer (11) (Qty. 16 each).

b) Attach each lower support assembly (1, 2) loosely to the stabilizer (6) and

t he tailboom (5) using the screw (12) and the washer (11) (Qty. 16).

c) Tighten the screws (10) attaching the stabilizer (6) to each upper support (3, 4) first.

d) Tighten the screws (12) attaching the stabilizer (6) to the horizontal flange of each

lower support assembly (1, 2).

e) Tighten the screws (13) common to the tailboom skins (7, 8) last.

f) Complete the installation by installing the aft screw, nut and washer (9) at the most aft hole location on each side of the tailboom (5).

43) Apply a bead of sealant ( C

- 392 ) to seal outboard edges of upper & lower supports (3, 4 1 and 2) and gaps forward of stabilizer leading edge and aft of stabilizer trailing edge. Allow sealant to cure.

44) Restore the primer ( C

- 204 ) and aircraft paint finish as requ ired.

45) Annotate aircraft technical records to indicate that you completed this Technical

Bulletin.TB 407

- 01

- 33

Page 14 of 23

PART II: Replacement of lower support angles (14 or 15).

- NOTE

Do this part only if you cannot get an acceptable gap between the upper or lower support s (1, 2, 3, 4) and the stabilizer (6) surface.

1) Remove the affected lowers support assembly (1,2) from the tailboom (5).

2) Remove all the rivets that hold the support angle (14, 15) to the mating closure plate (16,17). Separate parts and discard the drille d support (14,15).

3) Install the closure plate (16,17) onto the tailboom (5) and secure in place with the screws (13). Tighten each screw . .

4) Put the new angle (14,15) in position against the lower surface of the stabilizer (6)

and the outboard face of the closure plate (16 or 17).

- NOTE

BHT recommends that you create an artificial gap to help with the shimming process described in Part I. Insert a strip of 2024T3 Al Alloy (1 inch wide X 2 inches long X 0.010 inch maximum thick (25.4 mm X 50.8 mm X .254 mm thick)) at two locations between flange of support angle (14,15) and lower surface of stabilizer (6).

5) Find the best fit with a 0.003 to 0.010 inch (0.08 to .254 mm) clearance between the stabilizer lower surface and the flange of the lower angl e. Hold this position while you mark with a fine tip felt pen on the horizontal flange of the angle, the

center location of the 8 holes that will be in line with the center of each insert in the stabilizer (6).

6) Mark the outline of the outer edge of the s upport angle (13, 14) onto the closure plate (16, 17) and draw one line near the front end of the angle (13, 14) running vertically through the lower edge of the angle, extending onto the closure plate (16, 17). Draw a similar line near the aft end of the angle (16, 17).

7) Remove the support angle (14 or 15) and the closure plate (16 or 17).

8) Use the marks that were made in Step 6 to align the support angle (14,15) with the closure plate (16,17) and clamp both parts together.

9) Use a drill #20 (0.160 inch (4. 09 mm) diameter) to transfer the 20 rivet holes from the closure plate (16, 17) to the support angle (14,15).TB 407

- 01

- 33 Page 15 of 23

10) Use a drill #4 (0.209 inch (5.30 mm) diameter) to transfer the front and aft screw holes from the closure plate (16, 17) to the support (14, 15).

11) Use a #40 drill (0.098 inch (2.49 mm) diameter) to pilot drill the centerline of each marks made earlier on the horizontal flange of the support angle (14, 15).

12) Use a #4 drill (0.209 inch (5.30 mm) diameter) to increase to final size, the 9

holes in t he horizontal flange of the support angle (14, 15). Deburr all holes.

13) Coat the faying surface of the support (14, 15) that will mate with the closure plate (16, 17) with a thin layer of sealant ( C

- 392 ) and assemble both parts using
20 rivets MS20470AD5.

14) Let sealant cure and prime all bare metal surfaces using primer ( C

- 204 ).

15) Install the new support assembly (1, 2) and do Part I of this bulletin.TB 407

- 01

- 33

Page 16 of 23

Figure 1. Horizontal Stabilizer Installation Procedure (sheet 1 of 8).TB 407

- 01

- 33 Page 17 of 23

Figure 1. Horizontal Sta bilizer Installation Procedure (sheet 2).TB 407

- 01

- 33

Page 18 of 23

Figure 1. Horizontal Stabilizer Installation Procedure (sheet 3).TB 407

- 01

- 33 Page 19 of 23

Figure 1. Horizontal Stabilizer Installation Procedure (sheet 4).TB 407

- 01

- 33

Page 20 of 23

Figure 1. Horizontal Stabilizer Installation Procedure (sheet 5).TB 407

- 01

- 33 Page 21 of 23

Figure 1. Horizontal Stabilizer Installation Procedure (sheet 6).TB 407

- 01

- 33

Page 22 of 23

Figure 1. Horizontal Stabilizer Installation Procedure (sheet 7).TB 407

- 01

- 33 Page 23 of 23

Figure 1. Horizontal Stabilizer Installation Procedure (sheet 8).