# Robinson Service Letter 56: Revision B

- Rights: © Robinson. Filed by the FAA in regulations.gov docket FAA-2013-0159, the docket of AD 2014-23-16. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Robinson Service Letter 56](https://openairdocs.org/service-documents/robinson/sl-56.md)
- Title as filed: U.S. DOT/FAA - Robinson Service Letter SL-56B and SL-32B
- Pages: 2
- PDF: https://openairdocs.org/files/sha256/18/2e/182e7b3a3f622aa111311ee44642ddef9618b5ead74e20bd36e750ade39f8bd3
- Page: https://openairdocs.org/service-documents/robinson/sl-56/file/182e7b3a3f62

## Text

This text is OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N.

### Page 1 (OCR)

ROBINSON
HELICOPTER COMPANY
2901 Airport Drive, Torrance, California 90505  Phone (310) 539-0508 Fax (310) 539-5198
Page 1 of 2
R22 SERVICE LETTER SL-56B
R44 SERVICE LETTER SL-32B
DATE: 30 April 2010
TO: R22 & R44 owners, operators, and maintenance personnel
SUBJECT: A016-4, C016-2, and C016-5 Main Rotor Blade Bond Maintenance
BACKGROUND: Debonding of main rotor blade skins can occur when the bond line
is exposed due to erosion of the blade finish or when corrosion occurs on the internal
aluminum tip cap. Proper inspection and protection (refinishing) of bonded areas is
required.
COMPLIANCE PROCEDURE:
1. Remove main rotor blade tip cover(s) and clean the blade(s).
2. Feather edge of paint bordering bare metal by hand-sanding spanwise with 220-grit or finer
wet-or-dry aluminum-oxide or silicon-carbide abrasive paper. Do not remove metal.
CAUTION
Do NOT use power tools or chemical paint strippers to remove paint.
3. Mask area to prevent overspray contamination.
4. Clean bare metal to be painted with a lint-free cloth dampened with enamel cleaner.
5. Prime bare metal, including any bare metal which will underlie tip covers, with at least
two coats of Desoprime CA7501 epoxy primer (or equivalent). Scuff primer prior to
applying second coat. Desoprime technical data is available online at:
http://www.ppg.com/coatings/aerospace/coatings1/CA_7501CF_0803.pdf
6. Apply flat black Dupont Imron 373-P-29950 and/or yellow Imron K0680HK polyurethane
enamel (or equivalent) to primed area in accordance with paint manufacturer's
recommendations. Dupont technical data is available online at (link is case sensitive):
http://pc.dupont.com/dpc/en/US/html/visitor/common/pdfs/b/product/dcf/OEM_Fleet/
imron5000_2-8.pdf
(OVER)

### Page 2 (OCR)

R22 SL-56B
R44 SL-32B
Page 2 of 2
CAUTION
If force-drying paint, do not exceed 175°F surface temperature on
blade; monitor blade temperature.
NOTE
Allow Imron paint to cure at least 72 hours before flying in erosive
conditions (such as drizzle, rain, or dust).
7. Install blade tip cover(s).
8. Make appropriate maintenance record entries.
Approximate Cost:
Parts: KI-188 Kit (if required), includes  $190
one quart each primer, black, & yellow

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