Airworthiness Directive · Amendment 39-11520 · Short Brothers Model SD3-60 SHERPA, SD3-SHERPA, and SD3-30 Series Airplanes
Short Brothers Model SD3-60 SHERPA, SD3-SHERPA, and SD3-30 Series Airplanes
All Model SD3-60 SHERPA and SD3-SHERPA series airplanes; and Model SD3-30 series airplanes as listed in Shorts Service Bulletin SD330-35-1, dated February 25, 1999; certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment adopts a new airworthiness directive (AD), applicable to all Short Brothers Model SD3-60 SHERPA and SD3-SHERPA series airplanes, and certain Model SD3-30 series airplanes, that requires replacement of existing oxygen system "O" rings with improved wear-resistant "O" rings. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent the loss of oxygen from the aircraft oxygen system, which could result in an insufficient supply of oxygen being provided to the airplane flight crew and passengers in the event of an emergency.
To prevent the loss of oxygen from the aircraft oxygen system, accomplish the following:
(a) Within 24 months after the effective date of this AD, replace oxygen system “O” rings, part number (P/N) MS28778, with improved wear-resistant “O” rings, P/N MS9068, in accordance with Shorts Service Bulletins SD360 Sherpa-35-2, dated February 25, 1999 (for Model SD3-60 Sherpa series airplanes); SD3 Sherpa-35-3, Revision 1, dated May 5, 1999 (for Model SD3 Sherpa series airplanes); and SD330-35-1, dated February 25, 1999 (for Model SD3-30 series airplanes); as applicable.
(b) As of the effective date of this AD, no person shall install an oxygen system “O” ring, P/N MS28778, on any airplane.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
