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Horizontal Stabilizer Aft Fitting inspection: Worthington Aviation has requested and has received an Alternate Method Of Compliance (AMOC) for Airworthiness Directive (AD) 89-12-08. This AD concerns the inspection criteria for the horizontal stabilizer splice (aluminum). The AD states, (paragraph C) “if cracks are found, replace the splice fitting prior to further flight, in accordance with the following IAI Service Bulletin entitled “Horizontal Stabilizer Assembly –Inspection, Repair and Improvement (AFC 2037), as appropriate”. The Service Bulletins listed do no reference the replacement of the fitting with the titanium fitting (453005-509) hence the continued inspection criteria remains in the body of the AD (paragraph B).
Since then IAI has come out with the -509 titanium fitting and had changed the AMM Ch 5 to reflect the changed times for inspection for this part.
This AMOC references the -509 titanium fitting and the changed inspection times for this fitting.

Please refer to the IAI AMM 5-20-06 pg 202
Contact Worthington for a copy of the AMOC for your records (ANM-116-08-212)

ATA 53

The inspection criteria will be changing for the fuselage in the areas of the chem. milled skins. The preliminary change will be to add the following: Removal of all sound deadening / insulation above floor level and accomplish a visual inspection in the areas of the chemically milled skins for corrosion. Then reinstallation of new insulation that will be adhered to the outer skin. This insulation will be easier to remove for subsequent inspections.

ATA 53

Fuselage Skin Corrosion
On April 3, 2007 a Westwind operator reported a cabin decompression due to a fuselage skin panel failing, the cause was severe corrosion. It was corroded in multiple places in the chemically milled areas hidden under the Insulation/Noise/Vibration Damping Pads.

A thorough inspection of adjacent fuselage skin panels and bulkheads was completed noting that the corrosion was contained to only the one panel which is located at the top aft portion of the fuselage between Fuselage Station 219.05 and Fuselage Station 269.87.

Please refer to the FAA AC 43-4A “Corrosion Control for Aircraft” document for details related to corrosion prevention.

A follow up investigation of the event is underway and if any fleet action is required it will be communicated accordingly