ASB MBB BK117 C-2-24A-008

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Effective for version: All

ALERT SERVICE BULLETIN

SUBJECT: ELECTRICAL POWER – Starter/Generator

Visual monitoring of the power display GEN AMPS on the VEMD when a

generator is deactivated

Revision number Date of issue

Revision 0 20101220

Summary:

On some helicopters there was a too high current flow when the generator had been deactivated (e.g.

during the ENGINE POWER CHECK). Under unfavorable circumstances this could cause a failure of

the generator. This situation, if not detected, could lead to a subsequent loss of electrical power and

thereby loss of relevant systems for a safe continuation of the flight. In order to prevent the generator

from getting damaged, this Alert Service Bulletin specifies the visual monitoring of power display GEN

AMPS on the VEMD.

Compliance:

Copies of the corresponding, attached pages must be inserted in the model–related flight manual immediately after receipt of this Alert Service Bulletin.

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1. PLANNING INFORMATION

1.A. EFFECTIVITY

1.A.1. Helicopters/installed equipment

MBB BK117 C-2, all models.

1.A.2. Non–installed equipment

Not applicable.

1.B. ASSOCIATED REQUIREMENTS

The pilots of the MBB BK117 C-2 must be informed of the content of this Alert Service Bulletin

immediately after its receipt and they must be told that the procedures i.a.w. the flight manual

pages attached to this Alert Service Bulletin must be respected.

1.C. REASON

On some helicopters there was a too high current flow when the generator was deactivated (e.g.

during the ENGINE POWER CHECK). Under unfavorable circumstances this could cause a

failure of the generator. This situation, if not detected, could lead to a subsequent loss of electrical

power and thereby loss of relevant systems for a safe continuation of the flight. In order to prevent

the generator from getting damaged, this Alert Service Bulletin specifies the visual monitoring of

power display GEN AMPS on the VEMD. When an error occurs the BUS TIEs on the overhead

panel must be switched off.

1.D. DESCRIPTION

Insert the flight manual pages in the model–related flight manual.

1.E. COMPLIANCE

1.E.1. Compliance at the works

Helicopters/installed equipment:

Copies of the attached pages must be inserted in the model–related flight manual before the

helicopter is delivered at the latest.

Non–installed equipment:

Not applicable.

1.E.2. Compliance in service

Helicopters/installed equipment:

(a) Copies of the corresponding, attached pages must be inserted in the model–related flight

manual immediately after receipt of this Alert Service Bulletin.

(b) When a generator is deactivated (e.g. during the ENGINE POWER CHECK), the power

display GEN AMPS on the VEMD must be visually monitored. When an error occurs the

BUS TIEs on the overhead panel must be switched off.

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Non–installed equipment:

Not applicable.

1.F. APPROVAL

Approval of this document:

The technical content of this document is approved under the authority of

DOA No. EASA.21J.034.

1.G. MANPOWER

Not applicable.

1.H. WEIGHT AND BALANCE

Not applicable.

1.I. EFFECT ON ELECTRICAL LOADS

Not applicable.

1.J. SOFTWARE MODIFICATION EMBODIMENT RECORD

Not applicable.

1.K. REFERENCES

Not applicable.

1.L. OTHER DOCUMENTS AFFECTED

The changes to the flight manual which are required as a result of this Alert Service Bulletin are

temporary and must be inserted i.a.w. the procedure described in Section 3.B.1. The temporarily

inserted flight manual pages will be incorporated in the FLM MBB BK117 C-2 with the next

revision.

1.M.INTERCHANGEABILITY OR MIXABILITY OF PARTS

Interchangeability:

Not applicable.

Mixability:

Not applicable.

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2. MATERIAL INFORMATION

2.A. MATERIAL: PRICE – AVAILABILITY – PROCUREMENT

Not applicable.

2.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT

Not applicable.

2.C. MATERIAL REQUIRED FOR EACH HELICOPTER/COMPONENT

Not applicable.

2.D. MATERIAL TO BE RETURNED

Not applicable.

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3. ACCOMPLISHMENT INSTRUCTIONS

3.A. GENERAL INFORMATION

Not applicable.

3.B. OPERATIONAL PROCEDURE

3.B.1. Procedure

(a) Copy the flight manual pages attached to this Alert Service Bulletin, cut them out and insert

them in the model–related flight manual.

(b) I.a.w. the FLM MBB BK117 C-2 the power display GEN AMPS on the VEMD must be visually monitored when a generator is deactivated (e.g. during the ENGINE POWER

CHECK). When an error occurs the BUS TIEs on the overhead panel must be switched

off.

3.B.2. Tests

Not applicable.

3.C. IDENTIFICATION

Confirm accomplishment of this Alert Service Bulletin by an entry in the historical record of the

helicopter.

3.D. OPERATING AND MAINTENANCE INSTRUCTIONS

Flight manual:

The pilots of the MBB BK117 C-2 must be informed of the content of this Alert Service Bulletin

immediately after its receipt and they must be told that the procedures i.a.w. the flight manual

pages attached to this Alert Service Bulletin must be respected.

AMM/maintenance manual:

Not applicable.

4. APPENDIX

Revised pages of the flight manual.

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