Ad/EC 120/18 - Lighting and Ancillary Control Unit (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.

Eurocopter EC 120 Series Helicopters

AD/EC 120/18 Lighting and Ancillary Control Unit 12/2008 TX

Applicability:	EC 120 B helicopters, all serial numbers, equipped with the emergency floatation gear option, incorporating emergency floatation gear lighting and auxiliary control unit (LACU) Part Number (P/N) 040101AB.
Requirement:	1.    Amend the Aircraft Flight Manual (AFM) to incorporate the following in-flight functional check:
Arm the emergency floatation gear by pressing the LACU "FLOAT ARM" pushbutton and reduce speed in accordance with Flight Manual Supplement 9.17.
·    If both lights of the pushbutton remain lit, continue the flight.
·    If one or both lights of the pushbutton do not remain lit, FURTHER FLIGHT OVER WATER IS PROHIBITED and only a single ferry flight without passengers is allowed to return the helicopter to a location where corrective action can be taken.
This may be accomplished by inserting a copy of this Directive into the AFM.  Paragraph 2.B.2 of Eurocopter EC 120 Alert Service Bulletin (ASB) 04A007 dated 18 September 2008 pertains to this subject.
2.    Perform the in-flight functional check as defined in Requirement 1.
3.    If, the “FLOAT ARM” pushbutton fails the in-flight functional check, remove the failed “FLOAT ARM” pushbutton and replace it with a serviceable unit in accordance with the instructions of Eurocopter EC 120 ASB 04A007 or later revision approved by the European Aviation Safety Agency (EASA) and the Aircraft Maintenance Manual, Task 31-42-00, 8-2.
Replacement of the pushbutton does not constitute terminating action for the repetitive checks required by this Directive.
Note:  EASA Emergency AD 2008-0177-E refers.
Compliance:	For Requirement 1 - Before next flight after the effective date of this Directive.

For Requirement 2 - Prior to each flight over water.

For Requirement 3 - Prior to the next flight over water.

This Airworthiness Directive becomes effective on 24 September 2008.

Background:

EASA has advised that several operators have reported unreliability of the latching pushbuttons on the LACU.  One of these pushbuttons, the "FLOAT ARM", is used to arm the emergency floatation gear to allow ditching in case of emergency.  If the "FLOAT ARM" pushbutton does not latch in the depressed position, the emergency floatation gear cannot be armed, which constitutes an unsafe condition for flights over water.

Investigations have revealed the anomaly is likely to be due to the bonding of these pushbuttons.  Design improvements for the pushbuttons are currently in progress and will be shortly available to operators.

For the reason described above, this Directive requires a repetitive in-flight functional check of the “FLOAT ARM” pushbutton prior to flying over water and, if the pushbutton fails to latch in the depressed position, prohibits further flight over water until replacement of the “FLOAT ARM” pushbutton with a serviceable unit.

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

22 September 2008