Citation Summer 2007

• Flap Flexible Drive Shaft End Fitting Cracks in Citation Models 650 and 750
• Don’t Mix and Match Static Wicks
• Foreign Object Damage (FOD)

Flap Flexible Drive Shaft End Fitting Cracks in Citation Models 650 and 750

— Ed Johnson

Inspections of Citation Model 650 and 750 aircraft require removal and inspection of the flexible drive shafts at certain specific intervals. The task gives instructions to inspect the swaged end fittings per instructions in the Service Air Maintenance Manual (SAMM) 140353. Para. III. A. (2) (b.) of the SAMM gives instructions to inspect the cuff at the back of the fitting for scoring, chipping, or cracking. This damage is usually caused by misalignment of the shaft end fitting in the casing causing the cuff to wear thin and crack and chip. No specific mention is made, however, to inspect the fitting in other areas for cracks.

We have found several instances where cracks have developed along the swage tooling marks just above the cuff area. The cracks run perpendicular to the swage tool marks and are generally visible with the naked eye, but are prominent with a 10X magnification. A close inspection of this area should be conducted during this inspection procedure.

If you would like more information on this topic or any Citation technical matter, please contact me by phone at 402.479.1555.

Don’t Mix and Match Static Wicks

— Justin Merkling

On primarily older Citations, there are two different types of static wicks that can be installed. The first type is brown plastic. These were the type originally installed on the aircraft. An optional service bulletin was issued to replace all static wicks with the second type–gray with a black tip. After replacement of the static wicks per the service bulletin, all the flight controls had to be balanced. Therefore it is important not to mix and match the two different types of static wicks on your flight controls as it could potentially affect your flight control balance.

Foreign Object Damage (FOD)

— Dick Hyde

Aviation experts agree that FOD inside or outside your aircraft can be extremely serious. External FOD may be nothing more than a small rivet or other object on the ramp or runway. Tire punctures are common with runway FOD. FOD also comes from objects flying or floating in the air. “Bird strikes” are common around bird fly-way areas, rivers and lakes. Other examples are blowing sand, dust or volcanic ash and wildlife on or near runways.

Internal FOD may be an object left behind after maintenance. It may be trapped behind a panel or floorboard. It may even be part of the airplane that was not returned to its proper place. Duncan Aviation technicians have found items ranging from tie-raps, avionic control buttons, pencils and even an auxiliary gear handle. FOD trapped under floorboards could be a potential hazard to the safe operation of an aircraft. Sharp objects found lying on wire bundles, hydraulic lines, pitot / static lines, etc. are especially dangerous and can have a chafing potential which can lead to catastrophic failure. Recently, Duncan Aviation technicians have seen a rise in the level of internal FOD.

Carelessness with FOD should not be tolerated and strict procedures must be adhered to. Duncan Aviation is extremely serious about FOD, and has an inspection process in place to ensure that all foreign objects, regardless of area of origination, are secured prior to panel / floor close up. Duncan Aviation advises that operators review FOD procedures at any maintenance facility you might be considering to be sure FOD is taken seriously.

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