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INFORMATION LETTER 412-17-81<br />
13 January 2017<br />
TO:<br />
All owners and operators of Model 412/412EP helicopters<br />
SUBJECT: AIR COMM CORPORATION SERVICE LETTER SL-374 Rev C AND<br />
SERVICE BULLETIN SB 412-112316.<br />
The purpose of this Information Letter is to achieve complete distribution of the attached<br />
supplier service directives to the current affected model technical publications<br />
distribution list on record by Bell Helicopter Textron.<br />
For any questions regarding this letter, please contact Air Comm Corporation:<br />
1575 West 124 th Avenue, Westminster, CO 80234 – 303-440-4075<br />
Claire Chennault Street, Addison, TX 75001 – 972-407-1234<br />
www.aircommcorp.com – info@aircommcorp.com<br />
IL 412-17-81<br />
Page 1 of 1<br />
Approved for public release.
Page 1 of 2<br />
SB 412-112316<br />
Rev N/C<br />
Service Bulletin<br />
Title:<br />
SB 412-112316 Bell 412 Compressor Mount Nut Cracks<br />
Date: November 23, 2016<br />
Applicability:<br />
Reference:<br />
Compliance:<br />
Bell Helicopter 412 Aircraft equipped with the Air Comm Air Conditioning<br />
System, all serial numbers. The system serial number is marked on the<br />
compressor mount.<br />
FAA STC # SR00066DE<br />
Recommended inspection within 20 flight hours, recurring re-inspection<br />
each 25 flight hr period per the current ICA “412AC-208M_Rev14”.<br />
A. Discussion:<br />
During inspection an operator has reported finding cracks in the nuts securing the compressor<br />
mount to the main transmission housing. Although the nuts remained intact and capable of<br />
securing the mount it is believed that continued use would eventually lead to failure of the nuts<br />
and subsequently a loss of rigidity of the compressor mount. The compressor mount is secured<br />
to the transmission by 6 fasteners; three close tolerance 3/8 shear bolts on the top (high side) of<br />
the mount and three 3/8 studs on the low end of the mount. The cracks have been found in the<br />
nuts securing the low end of the mount to the transmission studs. The nuts are made from<br />
MS21042 self-locking steel nuts modified in height to accommodate the stud length.<br />
B. Procedure:<br />
Referring to the photo on page 2, locate the 3 nuts identified at the lower end of the compressor<br />
mount and visually inspect in place for cracks. If cracks are found, replacement hardware can be<br />
obtained from the Air Comm Corporation Service Department. Please contact us at: Phone 303-<br />
440-4075, Fax 303-440-6355, or E-mail service@aircommcorp.com<br />
C. Approval:<br />
This bulletin is based on previously FAA-approved data.<br />
D. Weight & Balance:<br />
No change to aircraft weight & balance.<br />
Revision Issue Date Inserted By Approved by Description of Changes<br />
NC 11/23/16 JMB Initial Release<br />
1575 West 124 th Avenue, Westminster, CO 80234 303-440-4075<br />
4554 Claire Chennault Street, Addison, TX 75001 972-407-1234<br />
www.aircommcorp.com info@aircommcorp.com
Page 2 of 2<br />
SB 412-112316<br />
Rev N/C<br />
Compressor mount<br />
3 transmission studs<br />
w/Air Comm nuts<br />
1575 West 124 th Avenue, Westminster, CO 80234 303-440-4075<br />
4554 Claire Chennault Street, Addison, TX 75001 972-407-1234<br />
www.aircommcorp.com info@aircommcorp.com
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