AD/Bell 206/158 Amdt 3 Fuel Distribution System (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/BELL 206/158 Amdt 2 and issues the following 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.

Bell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters

AD/BELL 206/158 Amdt 3 Fuel Distribution System 12/2007

Applicability:

Bell Helicopter Textron Canada (BHTC), Model 206 series helicopters up to S/N 5305 inclusive.

Requirement:

1.    Inspect the grounding of the fuel pumps and solenoid valve, as per instructions provided in Part I of Alert Service Bulletin (ASB) 206-05-103, dated 11 February 2005, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

2.    Perform clamping of the purge hose and position the boost pumps as indicated, in accordance with Part II of ASB 206-05-103, Revision A dated 12 July 2006 or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

3.    Verify the installation of the restrictor as per the instructions provide in Part III of ASB 206-05-103, Revision A or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

4.    Verify the installation of a filter as per the instructions provide in Part IV of ASB 206-05-103, Revision A or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

5.    For helicopters requiring the filter, amend the maintenance program to require a recurring 24 month inspection and cleaning as indicated in Part IV, paragraph 2 of ASB 206-05-103 Revision A or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Note:  Transport Canada AD CF-2005-10R3 refers.

Compliance:

For Requirement 1 - Within the next 100 hours time in service, but no later than
22 December 2007.

For Requirement 2 - No later than 22 December 2007.

For Requirements 3, 4 and 5 - At the next 100-hour inspection but no later than
22 December 2007.

This Amendment becomes effective on 22 November 2007.

Background:

Transport Canada has advised that inadequate electrical grounding of the fuel boost pump and the fuel drain solenoid valve, combined with fuel hoses contact, could cause arcing in the main fuel cell which may in turn cause an explosion and resultant fire.

The original issue of this Directive required a one time inspection to ensure correct grounding and, if necessary the disconnection and stowage of the engine fuel purge hose.

Since Canadian Airworthiness Directive CF-2005-10 was issued, Transport Canada has determined that the purge hose relocation as per instructions provided in Part II of ASB 206-05-103, could cause an engine flameout in a low fuel, boost pump off, condition.  Amendment 1 revoked, Requirement 2 of the initial issue of this Directive and required the helicopter fuel purge hose to be returned to its previous configuration.

Further investigation revealed that the engine flameout was caused by absence of restrictor, part number 206-061-637-001 or 206-061-655-001.  Amendment 2 mandated purge hose installation and boost pump positioning in addition to verification of installation of a fuel restrictor and filter.

Amendment 3 changes the applicability section of this Directive to list Model 206 helicopters by serial number range disregarding the suffix of “A” or “B”.  This is due to some Model 206A helicopters being converted to Model 206B helicopters.

The original issue of this Directive became effective on 16 June 2005.

Amendment 1of this Directive became effective on 2 December 2005.

Amendment 2 of this Directive became effective on 25 October 2006.

David Punshon
Delegate of the Civil Aviation Safety Authority

12 October 2007