AD 2020-22-12 Requires A One-Time Inspection Of The Electrical Harnesses Located In The Fuel Tanks...

The FAA is adopting a new airworthiness directive (AD) for certain Polskie Zaklady Lotnicze Sp. z o.o. Model PZL M28 05 airplanes.

This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as defective thermo-shrinkable tubes installed on the electrical harnesses located in the fuel tanks. This AD requires a one-time inspection of the electrical harnesses located in the fuel tanks and, depending on findings, replacement of the affected harness. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective December 8, 2020.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain serial-numbered Polskie Zaklady Lotnicze Sp. z o.o. Model PZL M28 05 airplanes. The NPRM published in the Federal Register on May 14, 2020 (85 FR 28893). The NPRM proposed to correct an unsafe condition for the specified products and was based on MCAI originated by the European Union Aviation Safety Agency  (EASA), which is the Technical Agent for the Member States of the European Union. EASA issued AD No. 2018-0242,  dated October 8, 2018 (referred to after this as “the MCAI”), which states: During accomplishment of maintenance on an M28 05 military version airplane, torn pieces of thermo-shrinkable tubes were found in the header section of the main fuel tank. These tubes are installed on electrical harnesses located in the fuel tanks and serve as marking and protection devices against mechanical damage during manufacturing and servicing. Pieces of these tubes may travel with the fuel flow and may block the jet pump or reduce its performance, particularly in the centre-wing fuel tank, in which the jet pump is the only way of further transfer of fuel to the engine.

Subsequent investigation determined that degradation of the tube material was caused by a manufacturing deficiency, leading to insufficient material resistance against mechanical damage when a tube is located in a fuel.

This condition, if not detected and corrected, could lead to reduced fuel supply to the engines, inability to use all the fuel in fuel tanks and reduced available engine power, resulting in reduced aeroplane performance.

To address this potentially unsafe condition, PZL identified the batch of aeroplanes that are potentially equipped with thermo-shrinkable tubes having this manufacturing defect, and issued the [service bulletin] SB providing inspection and replacement instructions.

For the reasons described above, this [EASA] AD requires a one-time inspection of the electrical harnesses located in the fuel tanks and, depending on findings, replacement of the affected harness.

Polskie Zaklady Lotnicze Sp. z o.o. informed the FAA the potential for damage to the thermoshrinkable tubes does not progress with time. Therefore, the FAA determined repetitive inspections are not required. You may examine the MCAI on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-0473.

FMI: www.regulations.gov