AD 2022-03-04 Requires Incorporating Into Maintenance Records New Or Revised Life Limits...

The FAA is superseding Airworthiness Directive (AD) 80-13-10, AD 80-13-12 R1, and AD 2008-03-01, which applied to certain de Havilland (type certificate now held by Viking Air Limited) Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes.

AD 80-13-10 required repetitively inspecting the main landing gear (MLG) legs for cracks and corrosion. AD 80-13-12 R1 required repetitively inspecting each engine nacelle lower longeron for cracks and buckling. AD 2008-03-01 required incorporating inspections, modifications, and life limits of certain structural components into the aircraft maintenance program. Since the FAA issued those ADs, new and more restrictive airworthiness limitations have been issued for certain structural components. This AD requires incorporating into maintenance records new or revised life limits, modification limits, and inspection or overhaul intervals. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective March 17, 2022.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 80-13-10, Amendment 39-3812 (45 FR 43155, June 26, 1980) (AD 80-13-10); AD 80-13-12 R1, Amendment 39-4135 (46 FR 31251, June 15, 1981) (AD 80-13-12 R1); and AD 2008-03-01, Amendment 39 15350 (73 FR 5729, January 31, 2008) (AD 2008-03-01). AD 80-13-10 applied to de Havilland (type certificate now held by Viking Air Limited) Model “DHC-6 type” airplanes with certain MLG legs and required repetitively inspecting the weld juncture at the Y-joint of the MLG legs for cracks and corrosion. AD 80-13-12 R1 applied to certain serial-numbered de Havilland (now Viking Air Limited) Model “DHC-6 type” airplanes with intermediate or high floatation tires, skis, or floats and required repetitively inspecting each engine nacelle lower longeron for cracks and buckling. AD 2008-03-01 applied to all Viking Air Limited Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes and required incorporating the inspections, modifications, and life limits (retirement) of certain structural components, as contained in Revision 5 of the DHC-6 Product Support Manual (PSM) 1-6-11, into the aircraft maintenance program. The NPRM published in the Federal Register on November 8, 2021 (86 FR 61719).

The NPRM was prompted by Canadian AD CF-2019-02, dated January 9, 2019 (referred to after this as “the MCAI”), issued by Transport Canada, which is the aviation authority for Canada. The MCAI applies to all Viking Air Limited (formerly de Havilland) Model DHC-6 series 1, DHC-6 series 100, DHC-6 series 110, DHC-6 series 200, DHC-6 series 210, DHC-6 series 300, DHC-6 series 310, DHC-6 series 320, and DHC-6 series 400 airplanes.

The MCAI states:

• The airworthiness limitations for DHC-6 aeroplanes are defined and published in the Viking Air Ltd. (Viking) Airframe Airworthiness Limitations Manual, Product Support Manual (PSM) 1-6-11, approved by Transport Canada. The instructions contained in PSM 1-6-11 have been identified as mandatory actions for continued airworthiness. Failure to comply with those instructions could result in an unsafe condition.
• Viking Air Ltd. published Revision 9 of PSM 1-6-11 earlier in 2018. Revision 9 of PSM 1-6-11, dated 30 April 2018, includes some new and/or more restrictive limitations than those contained in Revision 5. For the reason described above, this [Transport Canada] AD requires implementation of the actions specified in PSM 1-6-11 Revision 9.
• The compliance requirements for several of the tasks in PSM 1-6-11 were previously a range of flight hours and flight cycles. With Revision 9 of PSM 1-6-11, the range-based requirements have been changed to specific flight hours and flight cycle limits. This [Transport Canada] AD provides a phase-in allowance for those limitations so that operators will have the opportunity to schedule the modifications and inspections required by the limitations. The phase-in allowances are intended to mitigate the impact of changing from compliance ranges to compliance limits for aeroplanes that are approaching or have exceeded the limits on the effective date of the [Transport Canada] AD.

  

• Revision 9 of PSM 1-6-11 also includes some airworthiness limitations that were previously contained in service bulletins (SB) or other PSMs. Some of those limitations were mandated by [Transport Canada] ADs, specifically AD CF-80-06, CF-81-07R4 and CF-95-12. Because the affected limitations will now be controlled in PSM 1-6-11, the above mentioned [Transport Canada] ADs are superseded by this [Transport Canada] AD.

The following are new tasks in PSM 1-6-11 Revision 9:

1. Task 27-007 Replacement of flight control pulleys at Fuselage Station (FS) 270.
2. Tasks 32-001 and 32-002 Overhaul of main landing gear leg. There is an associated requirement to ensure that each affected part has been assigned a unique serial number.
3. Task 53-006 Inspection of the skin flange of machined frame at FS 239.
4. Tasks 54-003 to 54-010 Inspection of nacelle longerons.
5. Tasks 57-039 to 57-041 Inspection for wing upper skin disbond.

• Task 27-004 Replacement of flight control cables after spillage of corrosive materials in PSM 1-6-11 was limited to landplane configurations in previous revisions of PSM 1-6-11 but is now applicable to all configurations.
• The intent of the word “airframe” in PSM 1-6-11 Revision 9 is to include fuselage, nacelles, struts, interiors, cowlings, fairings, airfoils, landing gear and their controls. The airframe life limitation in PSM 1-6-11 Revision 9 is not intended to apply to components such as those in the fuel, electrical and hydraulic systems that are occasionally transferred from one aeroplane to another and may be salvaged from an aeroplane that is retired from service for use on an in-service aeroplane. PSM 1-6-13 defines current airworthiness limitations for DHC-6 avionics that are not addressed in this [Transport Canada] AD.

Model DHC-6-400 airplanes were type certificated after Transport Canada AD CF-2000-14 was issued and are subject to the same unsafe condition. You may examine the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-0960.

FMI: www.regulations.gov