407 SUBJECT - BellCustomer.com

TECHNICAL BULLETIN 407-11-94
18 October 2011
MODEL AFFECTED: 407
SUBJECT: LITTER DOOR SEAL IMPROVEMENT,
INSTALLATION OF.
HELICOPTERS AFFECTED: Serial number 53000 through 54061.
[Serial number 54062 and subsequent will have the
intent of this Bulletin accomplished prior to delivery.]
COMPLIANCE:
At Customer’s Option.
Several operators have reported that the existing litter door seal installation is
inadequate and allows water to leak inside the cabin both statically and in flight. A
redesigned litter door seal in combination with a new contour seal installation has been
developed to eliminate water ingress.
If the helicopter is equipped with Aeronautical Accessories (AA) high visibility crew
doors STC# SR09376RC-D, compliance with this Technical Bulletin could render the
crew doors harder to close depending on door shimming and adjustment. Contact AA
for assistance.
If the helicopter is equipped with Aeronautical Accessories (AA) aft passenger sliding
doors STC# SR01040AT, this Technical Bulletin is compatible; however, some minor
changes to the original installation may be required. Contact AA for assistance.
APPROVAL:
The engineering design aspects of this Bulletin are Transport Canada Civil Aviation
(TCCA) approved.
CONTACT INFO:
For any questions regarding this Bulletin, please contact:
Bell Helicopter Product Support Engineering - Light Helicopters
Tel: 450-437-2862 / 1-800-363-8023 / pselight@bellhelicopter.textron.com
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MANPOWER:
Approximately 10 man-hours are required to complete this Bulletin. This estimate is
based on hands-on time, and may vary with personnel and facilities available.
Taking into consideration adhesive cure times at ambient temperatures, approximately
24 hours are required to complete this Bulletin.
WARRANTY:
There is no warranty credit applicable for parts or labor associated with this Bulletin.
MATERIAL:
Required Material:
The following material is required for the accomplishment of this Bulletin and may be
obtained through your Bell Helicopter Textron Supply Center.
Part Number Nomenclature Qty
407-030-657-103 Litter door seal 1
120-285-1 Seal 70
120-210-008G048 Shim peelable (1) 1
(1) Shim required only if proper door adjustment may not be obtained during litter
door seal installation.
Consumable Material:
The following material is required to accomplish this Bulletin, but may not require
ordering, depending on the operator’s consumable material stock levels. This material
may be obtained through your Bell Helicopter Textron Supply Center.
Part Number Nomenclature Qty Reference *
MIL-PRF-81733 TYII Sealant 1 C-251
299-947-152TICL1 1OZ Adhesive (Dapcotac 3300) 5 C-300
299-947-152,TY1,CL2 Adhesive (RTV 732) 1 C-307
Acetone Solvent A/R C-316
80 Grit Abrasive paper A/R Commercial
Abrasive pad Abrasive pad A/R C-407
* C-XXX numbers refer to the consumables list in BHT-ALL-SPM Standard Practices Manual
SPECIAL TOOLS:
None required
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WEIGHT AND BALANCE:
Not affected
ELECTRICAL LOAD DATA:
Not affected
REFERENCES:
BHT-407-IPB Illustrated Parts Breakdown
BHT-407-MM Maintenance Manual
TB 407-98-11 Litter Door Seal, Modification of
PUBLICATIONS AFFECTED:
BHT-407-IPB Illustrated Parts Breakdown
BHT-407-MM Maintenance Manual
ACCOMPLISHMENT INSTRUCTIONS:
-NOTE-
For helicopter serial number 53000 through 53169 which
have not complied with TB 407-98-11, it is important to
comply with the following portion. Modify the top litter door
closeout and install the bottom door pad per TB 407-98-11
prior to accomplishment of this Bulletin.
-NOTE-
This installation requires that the door latches are properly
adjusted and that the door hinges have no excessive
looseness. Refer to BHT-407-MM Chapter 52.
1. Prepare helicopter for maintenance.
a. Prepare a clean work surface for the modification of the litter door.
b. Separate L/H aft passenger door (1, Figure 1) from the litter door (2) and put
aside. Remove litter door (2) from the helicopter. Refer to BHT-407-MM Chapter
52.
c. Remove interior plastic trim panel of the litter door (2). Refer to BHT-407-IPB
Illustrated Parts Breakdown Chapter 25 to view mounting hardware.
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2. Remove seals and prepare surfaces as follows:
a. Remove existing seal (2, Figure 2, Sheet 1) from the litter door (1) and on the
airframe’s side body door frame contour (4). Do not discard removed seals at this
time.
b. Remove existing litter door T-seal (3) and discard.
c. Remove residual adhesive and/or double sided tape from litter door (1) and side
body door frame contour (4) with Acetone (C-316), aided with a plastic scraper or
abrasive pad (C-407). Dry up surfaces with a clean dry cloth.
3. Prepare the installation of the new litter door seal (6, Figure 2, Sheet 2) as follows:
a. Prior to bonding seal (6) into position a litter door (1) adjustment check is
required. Temporarily position litter door (1) in its location onto the airframe
hinges.
-NOTE-
The next Steps to adjust the gap are critical. The position of
the door in relation to the frame will locate the litter door seal
(6) in its appropriate place for proper mating with the new
door frame contour seal (5) to be installed in a later Step.
b. Close the litter door (1) and latch. Pull the door outboard against the top and
bottom latched pins. Locate a feeler gauge 2 inches (5 cm) from the top aft end
corner of the litter door (1) and measure the gap as shown in Figure 3. The
optimal gap to obtain for proper sealing is 0.285 in +/- .005 (7.2 mm +/- 1.3).
(1) If the measured gap is smaller than the optimal gap, the top litter door striker
pin housing needs to have shims removed to push the door away from the
airframe sidebody. To adjust the litter door, refer to BHT-407-MM Chapter 52.
In conjunction with the adjustment verify that the door flushness remains
visually tolerable as shown in Figure 3.
(2) If the measured gap is greater than the optimal gap, the top litter door striker
pin housing needs to have shims added to pull the door closer to the airframe
sidebody. To adjust the litter door, refer to BHT-407-MM Chapter 52. In
conjunction with the adjustment verify that the door flushness remains visually
tolerable as shown in Figure 3.
(3) If the appropriate gap is obtainable, go to Step 4. If the specific gap range
cannot be obtained with the door adjustments; then shimming the litter door
seal P/N 407-030-657-103 into position is required. Double check your
readings and adjustments, if the gap is confirmed to wide, go to next Step c.
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c. To calculate the required shim thickness, take the measured gap and subtract
the optimal desired gap; the resultant will be the required shim thickness. As an
example, if the gap measured was 0.310 in (7.87 mm) minus the optimal gap of
0.285 in (7.24 mm) the resultant required shim thickness of 0.025 in (0.63 mm) is
required. Lightly heat the shim laminate P/N 120-210-008G048 with a heat gun to
aid splitting to the desired established shim thickness required.
d. Refer to Figure 4, mark and cut the shim’s protruding end flush with the seal.
Utilize the rectangular piece that was cut, to fill the remainder of the gap on the
aft top corner of the litter door. Sand a radius on the full length of the shim to
match the radius contour of the door. Trim any excess side material that could
interfere with the litter door seal installation.
e. Wipe faying surfaces with Acetone (C-316) and bond the shim into position with
sealant (C-251). Remove and fair excess sealant. Do not bond litter door seal at
this time, Go to Step 4.
4. Install seal (5, Figure 2, Sheet 2) onto the L/H passenger door frame contour (4) as
follows:
a. Utilize the seal that was safeguarded in the first Steps. Cut the new seal (5) to
the appropriate length plus an additional 4 inches (101.6 mm) of extra material to
work with during installation.
-NOTE-
To ensure proper bonding of seal (5) to airframe, in the
following steps, it is imperative that no white talcum powder
residue is left on the seal surface prior to adhesive
application. Wipe and clean seal surface meticulously.
b. Select the side of the seal with the part number markings as the surface to be
bonded down. Roughen faying surface of seal (5) with 80 grit abrasive paper to
ensure adherence. Wipe faying surface of the seal (5) and side body frame
contour (4) with Acetone (C-316). Wipe surface dry with a clean dry cloth.
c. Coat faying surfaces of the seal (5) and the edge of the door opening (4) with a
generous layer of adhesive (C-300). Allow 15-20 minutes for adhesive to set
before joining the two surfaces.
-NOTE-
Once dry, the adhesive (C-300) layers are ready for a one
time installation. Once the two faying surfaces have made
hard contact the seal cannot be pulled off and repositioned.
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If the seal is pulled the adhesive needs reapplication in that
specific area.
d. Start the installation of the seal (5) 2 inches (5 cm) aft of the lower forward corner
of the door opening (Figure 2, Sheet 2, Detail A). Make sure that seal (5) points
to the inside of the door opening. Install the seal (5) aft along the edge keeping
flush with the door opening and up flat against the interior bend radius of the side
body fairing. Join the extremities to match the ends of the seal (5). Refer to BHT-
407-MM Chapter 52.
5. Install litter door seal (6, Figure 2, Sheet 2 & 3) and seal (5) as follows:
a. Roughen faying surface of seals with 80 grit abrasive paper to ensure
adherence. Wipe faying surface of the seal with Acetone (C-316). Wipe surface
dry with a clean dry cloth.
b. Prepare the litter door (1). Wipe faying surfaces of the door with Acetone (C-
316). Wipe surface dry with a clean dry cloth.
c. Coat faying surfaces of the seal (6) and the door faying surfaces with a generous
layer of adhesive (C-300). Allow 15-20 minutes for adhesive to set before joining
the two surfaces.
-NOTE-
Once dry, the adhesive (C-300) layers are ready for a one
time installation. Once the two faying surfaces have made
hard contact, the seal cannot be pulled off and repositioned
unless adhesive is reapplied in that specific area.
d. Start the installation of the seal (6) at the top aft corner of the litter door (1). This
portion of the seal (6) is called the “T-seal” and is awkward to install since there
are three faces to match fit in the appropriate location in one movement. Keep
the top surface flush with the door edge and continue on positioning the seal
down to the bottom forward corner as shown on Figure 5, Sheet 1. When
bonding over the door hinge radius blocks, it is possible that the seal (6) does not
touch the most forward extremities of the radius blocks. If a gap is apparent, the
void is to be filled with sealant (C-251).
CAUTION
Do not cut the extremity flush, the overhang is required
further on.
e. From the bottom forward corner gradually transition the reference line from the
outside edge of door to interior door frame bend radius. Butt up edge of seal (6)
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flat against bend radius and bond remainder of the seal (6) as shown on Figure
5, Sheet 1.
f. Cut 4 feet of seal (5) to install on the litter door (1). Position the seal (5) making
sure it points aft or away from the door. Select the side of the seal (5) with the
part number markings as the faying surface to be joined. Cut at an angle and trim
to match fit with the bottom side of the T-seal installed in the previous Step as
shown on Figure 5, Sheet 1. Roughen faying surface of the seal (5) with 80 grit
abrasive paper to ensure adherence. Wipe faying surface of the seal and faying
surface of the litter door with Acetone (C-316). Wipe surface dry with a clean dry
cloth.
-NOTE-
To ensure proper bonding of seal (5) to airframe, in the
following steps, it is imperative that no white talcum powder
residue is left on the seal surface prior to adhesive
application. Wipe and clean seal surface meticulously.
g. Coat faying surfaces of the seal (5) and the door faying surfaces with a generous
layer of adhesive (C-300). Allow 15-20 minutes for adhesive to set before joining
the two surfaces.
-NOTE-
Once dry, the adhesive (C-300) layers are ready for a one
time installation. Once the two faying surfaces have made
hard contact, the seal cannot be pulled off and repositioned
unless adhesive is reapplied in that specific area.
CAUTION
Do not cut the seal (5) extremity flush, the overhang is
required in the next Step.
h. Start the installation of the seal (5) at the top aft corner below the “T-seal”. Bond
the faying surfaces along the edge of the door. Maintain flush with the door
opening and up flat against the interior bend radius of the door.
i. Refer to Figure 5, Sheet 1 & 2. Join the seal P/N 120-285-1 (5) with seal P/N
407-030-657-103 (6) as follows:
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CAUTION
If the next steps are not followed precisely as depicted in the
Figures the door will bind on the seal when closing
(1) Cut out center web of seal (5) as shown. Cut seal (1) length to match fit into
the interior of portion of seal (5).
(2) Roughen seal faying surfaces with 80 grit abrasive paper to ensure
adherence. Wipe faying surface of the seals faying surface with Acetone (C-
316). Wipe surface dry with a clean dry cloth.
(3) Coat faying surfaces of the seals with a generous layer of adhesive (C-300).
Allow 15-20 minutes for adhesive to set before joining the two surfaces.
(4) Bond seals together, cut seal to the appropriate angles as shown in Figure 5,
Sheet 2. Wipe surface clean with Acetone (C-316) and apply sealant (C-251)
to seal gap between the door and the mating corner of the two seals. Refer to
Figure 2 (Sheet 3), Detail C.
j. Temporarily install litter door and L/H passenger door on aircraft. Latch litter door
into position and slowly close the L/H passenger door. Refer to Figure 6 (Sheet 1
& 2) and confirm the following:
(1) The “T-seal” (6) correctly matches with seal (5) with side body door frame.
(2) The passenger door corner properly slides into the “T-seal” cavity. If required,
trim the top of seal (5) to avoid contact with the outer lip of the “T-seal”. Trim
as required any portion of the seal (5) that may cause binding when closing
the L/H passenger door.
(3) The bottom corner closes properly. No binding.
k. Once proper closing is confirmed, apply a thick bead of adhesive silicone (C-307)
onto the back side of the “T-seal”. Refer to Figure 2, Sheet 3.
l. At the butt line of seal P/N 120-285-1 (5) and “T-seal” (6), apply as shown Figure
2, Sheet 2, adhesive (C-307) to lightly fill any gap at tip of the seal (5) to create a
joint. During the cure time period, temporarily install a piece of anti-adhesion tape
on the interior surface of the L/H passenger door to allow closing.
m. Gently close the litter door and lock into position. Gently close the L/H passenger
door and latch into position. Wipe surface clean with Acetone (C-316) and apply
a bead of sealant (C-251) on the exterior lip of the “T-seal” and litter door as
shown in Figure 6, Sheet 2.
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n. Leave the doors closed in this position for 8 hours while adhesive and sealant is
curing.
6. Install seal P/N 120-285-1 (5) onto the side body door frame contour of the
remaining three doors as follows:
a. Repeat Step 4 for the crew doors, except the start line for the seals is
approximately 2 inches (50 mm) forward of the lower aft corner of the door
opening. Refer to BHT-407-MM Chapter 52
7. Adjust all doors and leak check installation as follows:
a. The new seal P/N 120-285-1 (5) installed is stiffer than the previous design.
Adjust the passenger and crew door striker pins as required. Refer to BHT-407-
MM Chapter 52. With the new seals installed, it is common to adjust the striker
pins outboard. If the aircraft is equipped with automatic door openers, it is
imperative to have them installed when conducting any adjustments to the striker
pins.
b. In the event that the L/H passenger door is remaining difficult to close, review
possible causes listed in Step 5, j. Additionally, from inside the cabin, visually
verify that the top forward section of the trim panel on the L/H passenger door is
not causing a binding effect between the door frame and the “T-seal”. If the trim
is found to interfere while closing the L/H passenger door, it is acceptable to cut
out only the portion of trim that firmly contacts the new “T-seal” installation.
c. If the door edge catches on the “T-seal” while closing, it is acceptable to sand a
radius on the door corner as described in Technical Bulletin 407-98-11, Figure 1,
Detail D.
d. Accomplish water leak check as follows:
(1) Place an observer in the cabin with a flashlight to look for water infiltrations.
(2) Close all windows. Close and latch all doors.
(3) Using a garden hose with tap water, at a distance of 4 to 6 feet away, spray
down and aft with a medium to dense spray pattern about the walkway
including top of door.
(4) Continue to spray water for 5 minutes.
(5) As an alternate means to check for leaks, slowly pour 5 liters of water over
the door’s sealing areas.
8. In case a leak is detected, remedy as follows:
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a. Verify that door latches are adjusted properly and that hinges do not have
excessive looseness.
b. Verify the bond line between the seals and the frames are proper. In the event
that the seal was pulled off slightly and repositioned during installation, the
affected area will need reapplication of adhesive (C-300).
c. Verify seal surfaces for cleanliness and condition.
-NOTE-
Always sand longitudinally to the direction of the seal
d. Verify the door mating surface with seal. Clean the contact area if found dirty.
Examine surface for scratches, grooves or discontinuities that may provide a
pathway for the water ingress. Lightly sand to provide a smooth surface or fill and
fair as required..
e. Repair or replace any of the above items as required. Repeat leak check until
satisfactory.
f. In the event that leaks are still apparent, call Product Support Engineering for
assistance. Refer to the cover page to obtain our contact information.
9. Return aircraft to service; properly reinstall trims, doors, and other items removed for
the accomplishment of this Bulletin.
-NOTE-
Seal P/N 120-285-1 installed onto the side body door frame
contour is stiffer and sticks out more than the original seal
removed. This difference makes it easier for the feet to snag
and debond the seal during frequent cabin boarding. At
customers option it is acceptable to apply a bead of
adhesive silicone (C-307) along the edge between the seal
and the frame to provide additional bond line strength.
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10. Make an entry in helicopter historical service records indicating compliance with this
Technical Bulletin.
Figure 1.Seal Installation overview
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Figure 2. Door seal installation (Sheet 1 of 3)
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Figure 2. Door seal installation (Sheet 2 of 3)
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Figure 2. Door seal installation (Sheet 3 of 3)
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Figure 3. Litter door adjustment (If required)
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Figure 4. Shim installation (If required)
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“T-Seal’
Lower Door hinge
radius block.
Transition from the
outside to the inside.
“T-seal” lower
corner
Litter Door
lower corner
1
2
Cut to Match Fit
seal 120-285-1
Cut the two seals at the junction as
shown. Cut out center web of seal
P/N 120-285-1 up 2 inches.
Figure 5. Installation of litter door seals (Sheet 1 of 2)
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Bond the two seals
together
View from top pushing down on seal
Refer to Figure 2 Detail C
to view the appropriate
cut angles required.
Figure 5. Installation of litter door seals (Sheet 2)
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Step J, (1) Confirm seals
correctly match
Step L, Apply adhesive (C-307)
View of the “T-Seal” from inside the cabin.
Step J, (2) Confirm door fit
Step J, Minor trimming of seal
edge as required.
Figure 6. Installation of the litter door and passenger door (Sheet 1 of 2)
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Litter and Passenger
bottom door corner.
Step J, (3) no binding
at bottom corner.
Step M Apply a bead of
sealant (C-251).
Figure 6. Installation of the litter door and passenger door (Sheet 2)
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