Airworthiness Directive · Amendment 39-16119 · Twin Commander Aircraft LLC Models 690, 690A, and 690B Airplanes
Twin Commander Aircraft LLC Models 690, 690A, and 690B Airplanes
This AD applies to the following airplane models and serial numbers that are certificated in any category:
| Models | Serial Nos. (S/Ns) |
|---|---|
| 690 | All S/Ns |
| 690A | All S/Ns except 11195 and 11279. |
| 690B | All S/Ns except 11361, 11383, 11527, and 11536. |
We are adopting a new airworthiness directive (AD) for certain Twin Commander Aircraft LLC Models 690, 690A, and 690B airplanes. This AD requires you to inspect between the surface of the left-hand (LH) and right- hand (RH) upper wing skins and the engine mount beam support straps for any signs of corrosion, replace the upper steel straps with parts of improved design, and modify both wings. This AD results from reports that corrosion was found between the mating surfaces of the wing upper skin surface and the engine mount beam support straps. We are issuing this AD to detect and correct corrosion on the engine mount beam support straps and the upper wing skins, which could result in failure of the engine mount beam support straps. This failure could lead to loss of the engine and possible loss of control of the airplane.
To address this problem, you must do the following, unless already done:
| Actions | Compliance | Procedures |
|---|---|---|
| (1) Inspect between the surface of the left-hand (LH) and right-hand (RH) upper wing skins and the engine mount beam support straps for any signs of corrosion and determine the extent of any corrosion found | Within the next 150 hours time-in-service after January 8, 2010 (the effective date of this AD) or within the next 12 months after January 8, 2010 (the effective date of this AD), whichever occurs first | Follow Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005, pages 1 through 14. |
| (2) Install modification access holes in the LH and RH lower wing skins | Before further flight after the inspection required in paragraph (e)(1) of this AD | Follow the Accomplishment Instructions, steps 1 through 4 and 6 through 9, of Twin Commander Aircraft Corporation Custom Kit No. 150, dated July 8, 1994, as specified in Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005. |
| (3) If corrosion damage is found during the inspection required in paragraph (e)(1) of this AD, perform necessary modification | Before further flight after the inspection required in paragraph (e)(1) of this AD | Follow Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005, Part II, Options A, B, or C, on pages 15 through 29 and 31. |
| (4) If corrosion damage is not found during the inspection required in paragraph (e)(1) of this AD, do the upper steel strap replacements | Before further flight after the inspection required in paragraph (e)(1) of this AD | Follow Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005, Part II, Option D, on pages 30 and 31. |
| (5) Install additional wing fasteners on the LH and RH wing | Before further flight after the inspection required in paragraph (e)(1) of the AD | Follow Gulfstream American Corporation Service Bulletin No. 182, dated March 2, 1981. |
Note: Although not required by this AD, we highly recommend compliance with Twin Commander Aircraft Corporation Service Bulletin No. 217, Revision No. 1, dated May 26, 1993, Engine Nacelle Firewall Reinforcement; and Twin Commander Aircraft LLC Alert Service Bulletin No. 239, dated February 13, 2006, Outboard Flap—Inboard Hinge Inspection & Reinforcement.
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
