AD/Bell 407/9 Amdt 3 Tailboom Skin (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 407/9 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) 407 Series Helicopters

AD/BELL 407/9 Amdt 3 Tailboom Skin 4/2008 DM

Applicability:

Model 407 helicopters with tailbooms part number 407-030-801-107 and
407-530-014-101/-103 installed.

Requirement:

Part I - Verification

a.    Verify whether tailboom part number 407-030-801-107 or 407-530-014-101/-103 is installed on the helicopter.

b.    Enter in the helicopter technical records the appropriate tailboom part number as identified above.

c.    If the tailboom identified is not affected by this Directive, annotate the helicopter technical records accordingly.

Part II - Surface preparation and initial inspection

Prepare the tailboom surface for “Daily Visual Check” in accordance with Part II, paragraph (1), items (a) to (e) of BHTC Alert Service Bulletin (ASB) 407-07-80 original issue, or later Transport Canada approved revision.

Inspect both areas for cracks (indicated as “Daily check area” on Figure 2 in ASB 407-07-80) using a 10x magnifying glass.

If a crack is detected, before further flight, replace the tailboom.

If no cracking is detected, ensure both surfaces are dry and protect each reworked area with a thin coat of clear coating in accordance with applicable paragraph of Part II, of ASB 407-07-80 original issue, or later Transport Canada approved revision.

Part III - Daily Visual Inspection

Perform a visual check of the tailboom in accordance with Part III, paragraphs (1) and (2) of ASB 407-07-80 original issue, or later Transport Canada approved revision.

If, as a result of the Part III Daily Visual Check inspection, a crack is detected, before further flight, replace the tailboom with a serviceable part.  Continue this inspection if the replacement tailboom is identified in the applicability section of this Directive.

Part IV - 100 hour Inspection

Perform a 100-hours inspection of the tailboom in accordance with Part IV of ASB 407-07-80 original issue, or later Transport Canada approved revision.

If, as a result of the Part IV 100-hour inspection, a crack is detected, before further flight, replace the tailboom with a serviceable part.  Continue this inspection if the replacement tailboom is identified in the applicability section of this Directive.

Part V - Terminating action

Replacement of the affected tailboom with part number 407-030-801-201/-203/-205, or later part numbers, constitutes terminating action to this Directive.

Note:  Transport Canada AD CF-2008-04 refers.

Compliance:

For Part I:

Within 10 flight hours after 15 February 2008.

For Part II:

Within 25 flight hours or 30 days after 15 February 2008, whichever occurs first.

For Part III:

Before the first flight of the day, during the pre-flight check.

For Part IV:

Within 100 flight hours after 15 February 2008, and thereafter at intervals not to exceed 100 flight hours.

This Amendment becomes effective on 15 February 2008.

Background:

There have been several reports of cracks to the tailboom skin on the left side in the area of the horizontal stabiliser.  The cracks were found by normal visual inspection. 

Amendment 1 limited the applicability to those helicopters equipped with certain part number tailbooms.  BHTC introduced a new tailboom with a chemically milled skin which is not subject to the inspections required by this Directive.

Amendment 2 introduced modifications to some of the existing tailbooms, a life limitation of 5,000 hours, and a new inspection interval of 150 hours.

Amendment 3 is issued in response to a new Transport Canada AD, which mandates new inspection requirements introduced by ASB 407-07-80.

David Villiers
Delegate of the Civil Aviation Safety Authority

13 February 2008