Airworthiness Directive · Amendment 39-21837 · Landing gear system
Daher Aerospace (Type Certificate Previously Held by SOCATA) Airplanes
This AD applies to Daher Aerospace (type certificate previously held by SOCATA) Model TB 20 and TB 21 airplanes, all serial numbers, certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for all Daher Aerospace (type certificate previously held by SOCATA) Model TB 20 and TB 21 airplanes. This AD was prompted by 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 cracks on the main landing gear (MLG) legs. This AD requires repetitively inspecting the MLG and performing all applicable corrective actions. The FAA is issuing this AD to address the unsafe condition on these products.
(1) Before the MLG exceeds 16,000 landings since first installation on an airplane or within 200 landings after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 3,200 landings, accomplish the magnetic particle inspection on each MLG for cracks in the left-hand and right-hand MLG leg and take all applicable corrective actions before further flight in accordance with the Description of Accomplishment Instructions in Daher Aerospace Service Bulletin SB 10-154-32, dated September 2019, except you are not required to contact the manufacturer. Instead, repair using a method approved by the Manager, International Validation Branch, FAA; the European Union Aviation Safety Agency (EASA); or Daher Aerospace's EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature. For a repair to be approved as required by this paragraph, the approval letter must specifically refer to this AD.
(2) For the purposes of this AD, any maneuver resulting in weight on the MLG for any duration of time after initial takeoff counts as a landing. If the number of landings for the MLG is unknown, multiply the number of airframe hours by a factor of 3.6 and round up to the nearest whole landing.
