AD/JBK 117/24 Generator Control Unit Inspection of the GND Terminal (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Kawasaki BK 117 Series Helicopters

AD/JBK 117/24 Generator Control Unit - Inspection
of the GND Terminal 7/2006 DM

Applicability:

Kawasaki BK117 series helicopters.

Requirement:

1.    Carry out a visual inspection of the terminal lug connected with terminal E of the starter generator and measure the resistance of the electrical wires between the starter-generator and the Generator Control Unit (GCU) in accordance with Kawasaki Service Bulletin KSB-117-272A dated 27 April 2006.

2.    If necessary, replace the terminal lug in accordance with KSB-117-272A.

3.    Repeat the same inspection and measurement as at Requirement 1.

4.    Repeat the Requirement 1 inspection and measurement.

5.    Insert a copy of the applicable Annex, by helicopter serial number, in front of the applicable page of the Aircraft Flight Manual (AFM) Section 3 - Emergency and Malfunction Procedures.

Note:  JCAB AD TCD-6850-2006 refers.

Compliance:

For Requirement 1 - Within 50 flight hours or the next 50 flight-hours inspection, whichever occurs first, after the effective date of this Directive.

For Requirement 2 - Before next flight immediately following the Requirement 1 inspection.

For Requirement 3 - Repeat the Requirement 1 inspection and measurement at the 300 hour inspection.

For Requirement 4 - Following any removal/installation of the starter-generator, or the wires connected to the starter-generator.

For Requirement 5 - Before further flight after the effective date of this Directive

This Airworthiness Directive becomes effective on 15 May 2006.

Background: In flight, a break occurred in the wire connected to the GND terminal (terminal E) of the starter-generator.  Voltage control by the generator control unit (GCU) was interrupted resulting in an overvoltage condition causing damage to several pieces of electronic equipment.

James Coyne
Delegate of the Civil Aviation Safety Authority

11 May 2006

Annex A

BK117 Helicopters Serial number 1001 through 1003 and 1005
and NOT accomplished KSB-117-012

GEN I  or         GEN II

(amber)   (amber)

Fault condition

Corrective action

Overvoltage condition caused by wire broken

(1) Voltmeter   - Check If voltmeter indication exceeds 30V: NOTE:   In case of overvoltage failure, the GEN caution light of normal generator side turns on. (2) GEN TRIP switch    - I and II (3) Both GENERATOR switch                   - OFF (4) Normal GENERATOR switch               - RESET, then ON,      (relevant to GEN caution   if necessary       light which turned on first) (5) If generator load exceeds 110A, cut off       unnecessary electrical load. LAND AS SOON AS PRACTICABLE If voltmeter indication NOT exceeds 30V Original EMERGENCY AND          MALFUNCTION PROCEDURES        - Perform

Annex B

BK117 Helicopters Serial number 1001 through 1003 and 1005 and KSB 117 -012 accomplished.
BK117 Helicopters Serial number 1004, 1006 through 1008 and 1010 through 1024

GEN I or         GEN II

(amber)   (amber)

Fault condition

Corrective action

Overvoltage condition caused by wire broken

(1) Voltmeter    - Check

If voltmeter indication exceeds 30V:

NOTE:   In case of overvoltage failure, the GEN
caution light of normal generator side
turns on.

(2) GEN TRIP switch    - I and II

(3) Both GENERATOR switch                   - OFF

(4) Normal GENERATOR switch               - RESET, then ON,
     (relevant to GEN caution   if necessary
      light which turned on first)

(5) If generator load exceeds 110A, cut off
       unnecessary electrical load.

LAND AS SOON AS PRACTICABLE

If voltmeter indication NOT exceeds 30V

Original EMERGENCY AND
         MALFUNCTION PROCEDURES        - Perform

Annex C

BK117 Helicopters Serial number 1009 and 1025 through 1109

GEN I or         GEN II

(amber)   (amber)

Fault condition

Corrective action

Overvoltage condition caused by wire broken

(1) Voltmeter    - Check

If voltmeter indication exceeds 30V:

NOTE:   In case of overvoltage failure, the GEN
caution light of normal generator side
turns on.

(2) GEN TRIP switch    - I and II

(3) Both GENERATOR switch                   - OFF

(4) Normal GENERATOR switch               - RESET, then ON,
     (relevant to GEN caution   if necessary
      light which turned on first)

(5) If generator load exceeds 110A, cut off
       unnecessary electrical load.

LAND AS SOON AS PRACTICABLE

If voltmeter indication NOT exceeds 30V

Original EMERGENCY AND
         MALFUNCTION PROCEDURES        - Perform

Annex D

BK117C-1 Helicopters

GEN I  or         GEN II

(amber)   (amber)

Fault condition

Corrective action

Overvoltage condition caused by wire broken

(1) Voltmeter    - Check

If voltmeter indication exceeds 30V:

NOTE:   In case of overvoltage failure, the GEN
caution light of normal generator side
turns on.

(2) GEN TRIP switch    - I and II

(3) Both GENERATOR switch                   - OFF

(4) Normal GENERATOR switch               - RESET, then ON,
     (relevant to GEN caution   if necessary
      light which turned on first)

(5) If generator load exceeds 110A, cut off
       unnecessary electrical load.

LAND AS SOON AS PRACTICABLE

If voltmeter indication NOT exceeds 30V

Original EMERGENCY AND
         MALFUNCTION PROCEDURES        - Perform

Annex E

BK117C-2 Helicopters

CAUTION INDICATIONS

GEN DISCON

           or         GEN DISCON

(SYSTEM 1)   (SYSTEM 2)

Conditions /Indications
Overvoltage condition caused by wire broken

Procedure
1. DC voltage indication   — Check

If voltage indication exceeds 30V:

NOTE:

      In this condition, normal generator is disconnected first from the power distribution system then relevant caution light turns on

2. Both GEN switch    — OFF

3. Normal GEN switch    — RESET then NORM

(relevant to the caution indication if          necessary

   which turned on first)

4. DC Voltage indication, GEN and BAT

current indications    — Monitor

If electrical power from battery is supplied:

5. Electrical consumers   — Reduce as much as

             possible

6. LAND AS SOON AS PRACTICABLE

NOTE: One generator alone will provide sufficient power for normal services.

If voltage indication NOT exceeds 30V:

2. Original EMERGENCY AND MALFUNCTION PROCEDURES              —Perform