Airworthiness Directive · Amendment 39-18704 · Flight controls
Saab AB, Saab Aeronautics (Formerly Known as Saab AB, Saab Aerosystems) Airplanes
This AD applies to Saab AB, Saab Aeronautics (formerly known as Saab AB, Saab Aerosystems) Model 340A (SAAB/SF340A) and SAAB 340B airplanes, certificated in any category, as identified in paragraphs (c)(1) and (c)(2) of this AD.
(1) Model 340A (SAAB/SF340A) airplanes, serial numbers 004 through 159 inclusive.
(2) Model SAAB 340B airplanes, serial numbers 160 through 459 inclusive, except serial numbers 170, 342, 362, 363, 367, 372, 379, 385, 395, 405, 409, 431, 441, and 455.
We are superseding Airworthiness Directive (AD) 2012-24-06 for certain Saab AB, Saab Aeronautics Model 340A (SAAB/SF340A) and SAAB 340B airplanes. AD 2012-24-06 required replacing the stall warning computer (SWC) with a new SWC that provides an artificial stall warning in icing conditions, and modifying the airplane for the replacement of the SWC. This new AD adds airplanes to the applicability, and adds requirements to replace the existing SWCs with new, improved SWCs, and to modify the airplane for the new replacement of the SWC. This new AD also reduces the compliance time for replacing the SWCs. This AD was prompted by a determination that airplanes with certain modifications were excluded from the applicability in AD 2012-24-06, and are affected by the identified unsafe condition; and that the SWC required by AD 2012-24-06 contained erroneous logic. We are issuing this AD to prevent natural stall events during operation in icing conditions, which could result in loss of control of the airplane.
For airplanes identified in paragraphs (g)(1) and (g)(2) of this AD: Within 30 days after the effective date of this AD, do the deactivation specified in paragraph (g)(1) or (g)(2) of this AD, as applicable to airplane configuration, in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-27-116, dated October 18, 2013.
(1) For airplanes with a basic wing tip that has been modified using Saab Service Bulletin 340-27-098: Deactivate the stall speed curves in the SWC having part number (P/N) 0020AK6.
(2) For airplanes with an extended wing tip that has been modified using Saab Service Bulletin 340-27-099: Deactivate the stall speed curves in the SWC having P/N 0020AK7.
Within 3 months after the effective date of this AD: Do the replacement specified in paragraph (h)(1) or (h)(2) of this AD, as applicable.
(1) For airplanes with basic wing tips: Replace all SWCs with new, improved SWCs having P/N 0020AK6-1, in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-27-121, dated July 11, 2014.
(2) For airplanes with extended wing tips: Replace all SWCs with new, improved SWCs having P/N 0020AK7-1, in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-27-122, dated July 11, 2014.
Before or concurrently with the accomplishment of the applicable requirements of paragraph (h) of this AD, do the actions specified in paragraph (i)(1) or (i)(2) of this AD, as applicable to airplane configuration.
(1) For airplanes on which either Saab AB Modification 2650 or Modification 2859 is not installed: Modify the stall warning and identification system, in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-27-120, dated July 11, 2014.
(2) For airplanes on which either Saab AB Modification 2650 or Modification 2859 is installed, or on which both modifications are installed: Modify the stall warning and identification system, in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-27-109, dated April 14, 2014.
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.
Aircraft
