TECHNICAL BULLETIN
No.
427-02-06
A Subsidiary of Textron Inc.
DATE
Date June 18, 2002
REV
Page
1 of 5
MODEL AFFECTED:
427
SUBJECT:
BATTERY RELAY DIODE, 2430CR4, Removal of
HELICOPTERS AFFECTED:
Model 427 helicopters serial number 56001
through 56030 and 58001 and 58002
[Model 427 helicopters serial number 56031 and
subsequent and 58003 and subsequent will have the
intent of this bulletin accomplished prior to delivery]
COMPLIANCE:
Bell Helicopter recommends accomplishment
of this bulletin.
DESCRIPTION:
The vendor of the over-current battery sensing relay P/N SX7EJ10, has changed
the tolerance of the circuitry inside the relay, the changes may result in the improper
operation of battery relay 2430KI .
This bulletin provides instructions for the removal of the redundant bus interconnect
diode (BUS ITCT diode), 2430CR4, P/N 30-251-24AC. The removal of diode
2430CR4, prevents possible incompatibility between the aircraft wiring and relay
2430KI, due to internal circuit tolerances.
APPROVAL:
The engineering design aspects of this bulletin are Transport Canada approved.
MANPOWER:
Approximately 1 man-hour is required to complete this bulletin. Man-hours are based
on hands-on time, and may vary with personnel and facilities available.
AN APPROPRIATE ENTRY SHOULD BE MADE IN THE AIRCRAFT LOGBOOK UPON ACCOMPLISHMENT
IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER
T.B. 427-02-06
Page 2 of 5
MATERIALS:
Required Material:
The following material is required for the accomplishment of this bulletin and may be
obtained through your Bell Helicopter Textron Supply Center.
Part Number
Nomenclature
MS27488-22
Sealing plug
Quantity
2
SPECIAL TOOLS:
M81969/16-04
Removal / insertion tool
WEIGHT AND BALANCE:
Not affected
ELECTRICAL LOAD DATA:
Not affected
REFERENCES:
BHT-427-MM, Chapter 96
BHT-ELEC-SPM
PUBLICATIONS AFFECTED:
BHT-427-MM, Chapter 96
BHT-427-IPC, Chapter 96
ACCOMPLISHMENT INSTRUCTIONS:
1. Disconnect the battery (BHT-427-MM chapter 96) and external power from the
helicopter.
2. Gain access to the inside of overhead panel and locate terminal block 3940TB2M
refer to figure 1.
427-02-06
Page 3 of 5
3. Remove diode 2430CR4 from 3940TB2MD and 3940TB2MF, using insertion /
extraction tool P/N M81969/16-04 refer to figure 2.
4. Remove wire P089A24 from 3940TB2MA and insert wire P089A24 into
3940TB2MF, using insertion / extraction tool P/N M81969/16-04.
5. Install sealing plugs MS27488-22 into 3940TB2MA and 3940TB2MD.
6. Close overhead panel.
7. Carry out an operational test of the Battery System (BHT-427-MM chapter 96).
8. Make an entry in the Helicopter historical record indicating compliance with this
bulletin.
9. Return the helicopter to flight status.
T.B. 427-02-06
Page 4 of 5
Overhead circuit breaker panel hinged down, view
looking forward.
Figure 1 Overhead circuit breaker panel.
427-02-06
Page 5 of 5
Figure 2 terminal Block 3940TB2