Metro Aviation, Inc. ASB Number: MA145

- 21B

- 003

Rev. B, 2 0 December 2013 Page 1 of 5 MA145

- 21B

- 003 

### MBB

- BK 117 C

- 2 (EC145)



# ALERT SERVICE BULLETIN

SUBJECT: TAIL ROTOR SYSTEM
AIR CONDI T IONING DRIVE PULLEY ATTACHMENT

Revision Number Issue Date

IR 23 April 2013

A 26 April 2013

B 2 0 Decem ber 2013

Summary:

Revision B of the Alert Service Bulletin details the procedure to install dual locking tabs on the existing EC145 air conditioning drive pulley attachment bolts.

Reason for Revision:

Please replace Revision A of Alert Service Bulletin MA145

- 21A

- 003 with Revision B (MA145

- 21B

- 003).

Compliance:

Compliance with this Alert Service Bulletin is prescribed in Section 1.EMetro Aviation, Inc. ASB Number: MA145

- 21B

- 003

Rev. B, 2 0 December 2013 Page 2 of 5 MA145

- 21B

- 003 

### MBB

- BK 117 C

- 2 (EC145)



# ALERT SERVICE BULLETIN

Air

- Conditioning

– Installatio n of Air

- Conditioning Drive Pulley

1. Planning Information A) Eff ectivi t y

i) Helicopters affected: Eurocopter MBB

- BK 117 A

- 3, A

- 4, B

- 1, and C

- 2 (EC145) helicopters equipped with a Metro Aviation vapor

- cycle air

- conditioning kit P/N

117MM

- 100

- 2 STC#SH3880SW

.

ii) Components affected: Metro Aviation vapor

- cycle Air C onditioning drive pulley

.

iii) Spare Parts affected: Not Applicable.

B) Concurrent Requirements: Not Applicable.

C) Reason: To improved bolt retention with dual locking features

D) Description: This Alert Service Bulletin details the procedure to install a dual locking tab on the existing EC145 air conditioning drive pulley attachment bolts.

E) Compliance:

It is recommended that this service bulletin be incorporated within the next 10 flight

hours. T his Service Bulletin supersedes A S B MA145

- 21 A

- 003

.

NOTE: Compliance times are for aircraft operating time not Air Condition er operating time

.

F) Approval: Engineering aspects are approved by t he FAA

.

G) Manpower: Approximately 4.0 man

- hours are required to add dual lock tabs.

H) Weight and Balance: Not Applicable.

I) Electrical Load Data: Not Applicable.

J) Software Accomplishment Summary: Not Applicable.

K) References: Metro Aviation, MBB

- BK 117 C

- 2 (EC145) Vapor Cycle Air

- Conditioner Equipment Maintenance Manual (117MM

- 100

- 02) & Installation drawing ( 117M

- 60 0

- 2 )

.

L) Other Publications affected: Not Applicable.Metro Aviation, Inc. ASB Number: MA145

- 21B

- 003

Rev. B, 2 0 December 2013 Page 3 of 5 MA145

- 21B

- 003 M) Interchangeability of Parts: Not Applicable.

2. Material Information A) Material : Three dual lock tabs (MAI

- 145

- DUAL LOCK TAB) will be provided per aircraft at no cost until Dec. 31, 2014. Fax a purchase order referencing the aircraft serial
number and Alert Service Bulletin number to Metro Aviation at (318) 698

- 5206.

B) Support Information: Not Applicable.

C) Material Necessary for Helicopter: 0.025” (0.6 2 mm) stainless steel safety wire

D) Material to be Returned: Not Applicable.

3. Accomplishment Instructions A) Remove Aircraft transmission and engine cowlings per AMM 71

- 11

- 00 Section 4

- 3 and

4

- 4

.

CAUTION: D o not remove the Air Condition ing drive pulley mount bolts without first

reliev ing tension f rom compressor drive belt.

B) Remove one (of three) bolt sets that install the a ir conditioning compressor belt pulley to the rotor brake disc. Note; do not remove all three sets at the same time.

C) Discard AN960

- 416 washer (originally installed under head of bolt securing pulley to

rotor disc )

.

D) Discard original lock tab P/N LN9023A10

- 1.4544.9

E) Install dual lock tab as shown below in View A

- A. Reinstall bolts IAW EC145 maintenance manual, Equipment Maintenance Manual 117MM

- 100

- 02, and drawing

117M

- 600

- 2.

F) Bend any two tabs (“A” T abs and “B” T abs) on each bolt that do not inte rfere with safety wire hole being used to secure the brake rotor disk bolts, as shown in View B

- B. The two tabs may be bent on the same side, or one each on opposing sides, as shown in Secondary Tab Bending. Bend down remaining single tab (tab “C”) as s hown in View
C

- C.

G) Safety wire bolts (using 0.025” (0.6 mm) safety wire) as shown View B

- B and IAW FAA
AC 43.13 1 B Chapter 7, Section 7, Paragraphs 7

- 122 through 7

- 12 5 . Safety wire may wrap around bent tabs , as required

.

H) Repeat above procedure for the re maining two sets of bolts (one bolt set as a time)

.

I) Reinst all Aircraft transmission and engine cowlings per AMM 71

- 11

- 00 Section 4

- 3 and

4

- 4.Metro Aviation, Inc. ASB Number: MA145

- 21B

- 003

Rev. B, 2 0 December 2013 Page 4 of 5 MA145

- 21B

- 003 FIG 1

COMPRESSOR BELT PULLEY BOLT SET (1 OF 3)

ROTOR BRAKE DISC DUAL LOCK TAB



## V IE W A

- A

VIEW LOOKING FORWARD SAFETY WIRE (1 OF 3)Metro Aviation, Inc. ASB Number: MA145

- 21B

- 003

Rev. B, 2 0 December 2013 Page 5 of 5 MA145

- 21B

- 003 “B” TABS

SECONDARY TAB BENDING BENT TAB

BENT TAB BENT TAB BENT TAB

TAB “C” BENT TABS

“A” TABS
BENT TAB BENT TABS



## VIEW B

- B

VIEW C

- C TAB “C”

ROTOR BRAKE DISC

COMPRESSOR BELT PULLEY PRIM ARY TAB BENDING SAFETY WIRE (1 OF 3)