FYI

Neither the manufacturer, IAI, nor its product support division (Worthington Aviation) can mandate the compliance of any service bulletin regardless of its designation (either “optional”, “recommended” or “mandatory”) with these exceptions:
1. Service Letters or bulletins, which are incorporated into the current manufacturer’s maintenance manual and /or assure continuous airworthiness. Example: SB1124 -55-020, found in the 1124 AMM, 5-20-06.
2. Service Letters or bulletins which are referenced in current FAA Airworthiness Directives
3. Service Letters or bulletins which are incorporated as part of the type certificate data sheets for the aircraft, engines, etc. The classification of service data by manufacturers with words such as ”optional”,” recommended “or “ mandatory” Should be perceived only as a measure of importance placed on the publication for the operators benefit. Please note that Worthington Aviation does not utilize the “mandatory” classification on any service publications.

In summary, 1121, 1123, 1124 and 1124A operators are obligated by FAA regulations to comply with a manufacturers service publication only if it is presented in one of the above three categories

ATA 27

We continue to find flap vanes not shimmed correctly. This condition will and does cause the potted inserts to fail which causes the forward vane rib and spar to crack. Vane replacement is very expensive. The correct way to install a vane is detailed in chapter 27-50-00, giving the correct amount of shimming washers. If the brackets seem to be under a spread pre-load, adjust the shims to correct. Remember that the instructions call out to re-install the same amount of shims previously removed –“BUT”- this is correct only if the previous technician installed the vane correctly.

ATA 55

When completing the installation of the flap actuators please accomplish all of the tests outlined in 27-50-00. This will help you have a smooth installation after accomplishing the prep work that is outlined in the AMM.

ATA 55

Horizontal pitch trim rod end adjustments are distinctly different even though the actuator itself is the same for both part numbers (543502-1 for the 1124 and 543502-501 for the 1123 and 1124A). Due to the critical nature of the adjustment, ordering and installing the correct unit cannot be over emphasized. The proper adjustment and configuration is preset and the parts marked accordingly on all Worthington Aviation stock actuators.

ATA 29

Does your emergency hydraulic pump cycle too often? The problem could be a faulty thermal relief value. If there is no evidence of external leakage the thermal relief valve should be suspect for bypassing. This valve performs two functions, it provides pressure relief at 1250 +/- 100 psi.and has a built-in check valve to prevent pressure from backing up thru the pump. This happens to be the only check valve in the emergency hydraulic system. Emergency pressure should hold for at least 60 seconds and pump running time should not exceed 45 seconds.

The hydraulic restrictors in the thrust reverser system can cause erratic operations of the thrust reverser if they are installed in the wrong port of the T/R actuator. The restrictor and the regular union are similar in appearance and can be interchanged if not properly identified before installation. The restrictor should be installed in the “stow “line port and the regular union should be installed in the “extend” line port.