Field Service Bulletin
Composite Cover Finish (Paint) Re-Work:
Spider Cracking

ENP-312
May 21, 2015

1. Introduction
This bulletin is intended to provide information on what is required to properly re-finish “spider
crack” damage on composite covers used on Agility Fuel Systems for CNG, as shown in Figures 1
and 2. It will be useful to repair personnel for finding and using compatible materials and finishes
for re-work. These guidelines are limited to repairs for fiberglass substrate work. These are
guidelines from a composite repair material manufacturer and are not intended to replace
procedures by experienced automotive paint and body workers.

Figure 1: Examples of paint and composite damage (spider cracks) covered in this bulletin.

Figure 2: Example of step pad composite damage covered in this bulletin.

ENP-312: Composite Cover Re-Work: Spider Cracks

2 of 5

2. Affected Units
This procedure applies to any Agility Fuel Systems configuration with composite covers with paint
and composite surface cracking.

NOTE
Pre-authorization is required for any warranty claims. Before any work is started, take
photos of the vehicle and condition of the paint, and submit to Product Support (949-2677745 or [email protected]) as part of your request for performing warranty repair.
Keep records of the vehicle VIN or fleet unit number as well. When work is completed, take
photos of the vehicle and send to Product Support so we have “before” and “after”
documentation.

3. Tools and Materials
1.
2.
3.
4.
5.
6.
7.
8.

22,000 RPM air grinder, 3/16-in. diameter orbit, Jonesway or similar
Dual action orbital sander, 3M 20317 or similar
Sandpaper for the above, 180-, 220-, 280-, 320- and 360-grit
Grinding bit, round grind bit for fiber glass, McMaster-Carr 4257A33 or similar
Hand/power tools to remove composite covers for refinishing
Body gap filler, Duraglas 24030 Gap Filler
Evercoat Metal Glaze 100416 Polyester Finishing and Blending Putty
Cleaning solvent, Axalta 2319™ lacquer thinner or equivalent

For additional paint materials see ENP-271, “Composite Cover Finish (Paint) Re-Work:
Chipping and Peeling” and ENP-290, “Composite Cover Finish (Paint) Re-Work:
Bubbles and Blisters.”

WARNING: Wear personal protective equipment (PPE) against dust and
fumes during the re-finishing process.

4. Remove the Outer Covers
5. Procedure – Surface and Crack prep

NOTE
If there has been a major structural failure of the composite, these procedures will
not be sufficient.
1. For shallow surface cracks as shown in Figure 1, use a DA grinder with 24-36 grit sanding
paper to remove paint and fiberglass gel coat.
2. Remove any residual particles and dust in preparation for filler. Refer to the Duraglas
technical data sheet for detailed surface preparation information.
3. For step pad cracks and deep surface cracks as shown in Figure 2, grind along the cracks,
getting into the substrate, but not through the substrate. See Figure 3.
4. Thoroughly clean the area.

ENP-312: Composite Cover Re-Work: Spider Cracks

3 of 5

Figure 3: Grinding the composite crack
5. Mix the Duraglas 24030 filler.
6. Apply the filler to the cracked areas. Flatten and smooth the edges to form a fillet around
the joints.
7. When cured, sand all excess material smooth and feather edges to the original part
contour.
8. Inspect for grooves and or pinholes.
9. Apply Evercoat Metal Glaze filler per Manufacturer instructions to fill pinholes and further
smooth all surfaces.

Figure 4: The repair area after filler application and sanding.
10. Sand the surface, using 180 grit – do not grind into the fiberglass substrate.

ENP-312: Composite Cover Re-Work: Spider Cracks

4 of 5

11. Sand the repair area with 360 grit sandpaper in preparation for primer.
12. Prepare the surface in accordance with SSPC-SP-1 Solvent Cleaning. Use a local air
quality compliant cleaning solvent. 2319 or lacquer thinner equivalent. Inspect for
cleanliness, if oil or grease is present, repeat cleaning process.
13. Allow a minimum of sixty minutes from last filler application before priming and painting.
Refer to Agility Fuel Systems document, “Composite Cover Finish (Paint) Re-Work: Chipping and
Peeling,” ENP-271.

7. Inspection
All prepared surfaces can be inspected and approved by an owner’s representative prior to primer
application and prior to topcoat application, and after primer and topcoat application.
Dry film thickness of each coat must be measured as described in ASTM D1186 (ferrous
substrates) or D1400 (non-ferrous surfaces).
The completed system must be inspected visually for skips, holidays, hiding, and uniform color.
Defects shall be repaired before final acceptance.

8. Warranty Information
This procedure may or may not be covered under warranty. Consult Product Support before
attempting repairs to finishes and body work.

9. Attachments
Duraglas Technical Data Sheets, Mixing and Application Information for each finish product.
If you have any questions, contact Agility Fuel Systems Product Support at 949-267-7745 or
[email protected].
Agility Fuel Systems
Product Support
1815 Carnegie Ave
Santa Ana, CA 92705 USA

Proprietary Statement
The information provided within this document is proprietary and confidential. All prior versions,
including updates and revisions forwarded separately, are proprietary. The information provided by
Agility Fuel Systems to its customers and clients is solely for the use of those customers and
clients. No portion of this manual may be reproduced or distributed without express written consent
of Agility Fuel Systems. Agility Fuel Systems reserves the right to utilize the intellectual property
contained within this publication as content for any other publication produced by Agility Fuel
Systems.
Trademark Notice
Agility Fuel Systems® is a registered trademark of Agility Fuel Systems. Drop-N-Go™ is a
trademark of Agility Fuel Systems. Trademarks of other manufacturers are the property of their
respective companies.
Revision

Description

Author

Approved By

Date

--

Initial Release

M. Gustafson

A. Bhakta

5/21/15

ENP-312: Composite Cover Re-Work: Spider Cracks

5 of 5