AD/DHC-8/55 Amdt 1 Horizontal Stabiliser Skin Disbonding Follow-up 7/2022 (Cth)

AIRWORTHINESS DIRECTIVE

On the commencement date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below repeals Airworthiness Directive (AD) AD/DHC-8/55 and issues the following AD under subregulation 39.001 (1) of CASR and subsection 33 (3) of the Acts Interpretation Act 1901. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct an 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.

De Havilland Canada (Bombardier) DHC-8 Series Aeroplanes

AD/DHC-8/55 Amdt 1 Horizontal Stabiliser Skin
Disbonding Follow-up 7/2022

Applicability:

All De Havilland Canada (DHC) DHC-8, Series 100 and 300 aircraft which have any horizontal stabilisers serial numbered CAP 003 through CAP 214 fitted.

Requirement:

1.    For Horizontal Stabilisers, Serial Numbers CAP 003 through CAP 050:

Perform an Ultrasonic Bond Inspection of the upper and lower skin panels (part number 85510025 and 85510026) for disbonding as outlined in DHC Non-Destructive Testing Manual, PSM 1-8-7A, Part 4, Section 55-00-01, as in force on the commencement date of this AD.

2.    For Horizontal Stabilisers, Serial Numbers CAP 003 through CAP 214:

Carry out the requirements stated in the Airworthiness Limitations List (AWL) of DHC Maintenance Program Manual PSM 1-8-7 (for series 100 aircraft) and AWL of DHC Maintenance Program Manual PSM 1-83-7 (for Series 300 aircraft), as in force on the commencement date of this AD.

Note:  Transport Canada AD CF-98-24 is the basis for this AD.

Compliance:

For requirement 1

1.    Unless already accomplished within the 3 months before 5 December 1998; repeat between 12 and 14 months after the initial inspection.

For requirement 2

2.    a.    For Horizontal Stabilisers Serial Number CAP 003 through CAP 050: Following the Compliance 1 repeat inspection, inspect within the next 2 years and thereafter at intervals not to exceed 2 years.

2.    b.    For Horizontal Stabilisers Serial Numbers CAP 051 through CAP 214:

i.     Where a past inspection fell due in 1998, unless already accomplished, perform the inspection as scheduled and repeat thereafter at intervals not to exceed 2 years.

ii.    Where a past inspection fell due in 1999, unless already accomplished, repeat thereafter at intervals not to exceed 2 years.

iii.   Where a past inspection fell due after 1 January 2001, perform the inspection 1 year earlier and repeat thereafter at intervals not to exceed 2 years.

Note:  The inspection interval has been reduced from 3 years to 2 years in accordance with Temporary Revision (TR) No. 63 of the AWL in the DHC Maintenance Program Manual PSM 1-8-7 for series 100 aircraft and TR No. AWL 3-70 of the AWL for the DHC Maintenance Program Manual PSM 1-83-7 for the 300 series aircraft.

For requirements 1 and 2

Disbonds beyond the local disbond limits defined in DHC document PSM 1- 8 -7A, Part 4, Section 55-00-01, as in force from time to time, must be repaired before further flight.

This AD commences on 15 April 2022.

Background:

As a result of the inspection required by AD/DHC-8/51, a total of four aircraft with serial numbers close together were determined to have disbonds of the doublers and stringers on the upper and lower skin panels of the horizontal stabiliser. This discovery indicates that the bonding process was defective on a single batch of skins. The follow-up inspections of this Directive will ensure that no further problems exist in the above single batch or other batches of the bonded skin panels.

Amendment 1 of this AD updates references to DHC NDT manual PSM 1-8-7A from part 5 to part 4. Transport Canada has issued an associated global AMOC AARDG‑2016/A48, which is available upon request from DHC.

David Punshon
Delegate of the Civil Aviation Safety Authority

7 April 2022