SB-10046739-9729

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
Prepared by:

Kalman Takacs
Field Service Engineer
256-241-1243

Approved By:

Dan Allen
Chief Engineer

Property and Top Bus Number: LA 45CLFW-03, 95000, 218000, 269000, 286000

Issue:

Door mechanism mounting bracket attachment to the sidewall.

Reason/ cause:

Still under investigation. Possible contributing factors:

Solution:



Improper surface preparation or adhesive application



Misaligned doors

On an as-needed basis, prepare and reinstall bracket per this work instruction
(SOI).

Work instruction number: L3/FSV-122
L4/QUA-003

Revision: Initial

Date: 09/06/2012
Revision: Initial
1/8

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
Number of affected buses:

as required

Estimate repair hours/bus:

8 hours

Necessary parts:
Bracket, entrance door,

NABI Part #: 802-4055-903,

as required,

Bracket, exit door,

NABI Part #: 802-4055-904,

as required,

PC-120, primer,

NABI Part #: 5016117,

as required,

Plexus AO-420, adhesive,

NABI Part #: 5016116,

1 tube / bracket,

Plexus MA-425, adhesive,

NABI Part #: 5016135,

1 tube / bracket,

Screw, #10x1, sheet, PH, SS,

NABI Part #: 270116,

3 / bracket

or

Necessary tools:
Regular hand tools (sockets, wrenches, screwdrivers, etc.), drill, angle grinder, 24G or 36G
abrasive disc, Plexus gun – air operated, brush, rag, acetylene torch (in case the bracket is not
completely separated), Sharpie marker pen

Work instruction number: L3/FSV-122
L4/QUA-003

Revision: Initial

Date: 09/06/2012
Revision: Initial
2/8

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
SAFETY PRECAUTIONS MUST BE FOLLOWED ACCORDING TO ACCEPTED INDUSTRY
STANDARDS AND LOCAL/PROPERTY REQUIREMENTS.
Note: this work instruction applies on both the front (entrance) and the rear (exit) doors.
1.
2.
3.
4.

Park the bus and apply the parking brake.
Turn off main battery disconnect switch.
Drain the air from the passenger door so the door panels can be moved freely.
Remove door mechanism assembly, door panels and door shafts. Refer to Maintenance
Manual.
5. Remove mounting bracket. If the bracket has not completely separated than heat up the
bracket and use pry bar to separate it from the bus structure. Do not damage the composite
bus structure. Follow local safety requirements. Have a fire extinguisher be available.
6. Remove any adhesive traces from the mounting bracket.

7. Grind the entire back surface of the mounting bracket (where it will be attached to the
composite structure) with 24G or 36G abrasive disc. Abrasive blasting (sand blasting) cleaning
process also can be used if equipment is available. The below pictures of sample plates show
what kind of quality must be achieved with the surface preparation.

Sand blasted surface

Work instruction number: L3/FSV-122
L4/QUA-003

Grinded surface
Revision: Initial

Date: 09/06/2012
Revision: Initial
3/8

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
8. Drill new 3/16” size holes 1” from the original holes. These holes are for the new sheet metal
screws. These sheet metal screws will keep the bracket in place while the adhesive cures.
Remove burr around the new holes.
9. Degrease back surface with acetone.
10. Apply PC-120 primer. Refer to SB-11-04-01.

First page of the NABI Service
Bulletin is shown. This document
has 2 pages

Work instruction number: L3/FSV-122
L4/QUA-003

Revision: Initial

Date: 09/06/2012
Revision: Initial
4/8

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
11. While the PC-120 primer dries, clean the composite structure: remove old adhesive and scuff
the surface gently with 24G or 36G abrasive disc. Do not cut the fiberglass/carbon fiber
layers! Just make the surface rough so the adhesive will bound better.

12. Degrease composite surface with acetone.
13. Mark the location of the bracket on the composite surface. See drawings below.

Work instruction number: L3/FSV-122
L4/QUA-003

Revision: Initial

Date: 09/06/2012
Revision: Initial
5/8

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
Front (entrance) door bracket
Plexus adhesive

36 mm / 1.42”

Rear (exit) door bracket

Plexus adhesive

36 mm / 1.42”

Work instruction number: L3/FSV-122
L4/QUA-003

Revision: Initial

Date: 09/06/2012
Revision: Initial
6/8

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
14. Place the bracket to the composite structure and check the gaps around the edges. Notice the
area where the gap is larger and ensure that these areas will be covered with the correct
amount of adhesive (see next step).
15. Apply a continuous bead of AO-420 or MA-425 Plexus adhesive to the prepared surface of the
bracket. Ensure to use the correct MC 10-24 mixing tube and applicator (gun) for the Plexus
adhesive. It is recommended to use air operated gun that would allow faster application. See
picture below how to cut the end of the mixing tube. Ensure that the two components of the
adhesive are mixing well (they are different colors for easy identification). The entire surface
has to be covered with adhesive. Apply more adhesive to those areas where larger gaps were
noticed. Note: the AO-420 adhesive has a very short working time. The bracket has to be
in place within 4 minutes after the plexus adhesive application was started on the
bracket.
Cutting the Plexus mixing tube

MC 10-24 mixing tube for Plexus adhesive

Plexus applicator with 380 ml
(13 oz.) adhesive tube

Plexus application on a sample surface
and not on the actual Vapor bracket
16. Place ¼” size flat washers on the bracket, over the new holes. These washers will provide the
required gap between the bracket and the composite structure. The min. required gap is 2-3
mm.
Work instruction number: L3/FSV-122
L4/QUA-003

Revision: Initial

Date: 09/06/2012
Revision: Initial
7/8

LACMTA 45CLFW: Door Mechanism Mounting Bracket
Attachment Repair
17. Push the bracket against the composite structure. Have a helper who can install the sheet
metal screws. Refer to SB-11-04-01. The adhesive has to squeeze all the way around from
underneath the bracket and through the holes of the original sheet metal screws. This will
indicate that the correct amount of adhesive was applied and it fills the gap between the
bracket and the composite structure. Remove excess adhesive all around the perimeter of
bracket and around the holes.
18. Let the Plexus cure for 1 hour. Do not install door parts nor move the bus during this time.
19. Reinstall removed door components. Refer to NABI Maintenance Manual.
20. Adjust the door per Maintenance Manual. The correct adjustment is critical: out of
adjustment may overload certain door components and may cause improper door
operation.
21. Remove all the tools from work area.
22. Check for completeness of work.
23. Turn the main battery disconnect switch(es) on.
24. Start the bus and make sure that the doors are working correctly.
25. Record bus number, date of repair and name of technician who completed the work.

Work instruction number: L3/FSV-122
L4/QUA-003

Revision: Initial

Date: 09/06/2012
Revision: Initial
8/8