AD 2013-22-09 Airworthiness Directives; Bombardier, Inc. Airplanes

Models named: DHC-8-400, -401, -402. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes, certificated in any category, serial numbers (S/N) 4001, 4003 and subsequent, equipped with rudder feel trim unit (RFTU) part number (P/N) 399500-1007.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Within 200 flight hours or two months after the effective date of this AD, whichever occurs first: Inspect the RTFU to determine whether the serial number is in the range from S/N 0008 through 0509 inclusive without a suffix `B,' in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-27-60, dated July 12, 2012. A review of airplane maintenance records is acceptable in lieu of this inspection if the serial number of the RFTU can be conclusively determined from that review. (1) If the RFTU's serial number is not in the range from S/N 0008 through 0509 inclusive, or if the serial number has a suffix `B,' no further action is required for this paragraph. (2) If the RFTU's serial number is in the range from S/N 0008 through 0509 inclusive, including those with a suffix `A,' but not including those with suffix `B': Within 200 flight hours or 2 months, whichever occurs first after the effective date of this AD, perform an operational check of the RFTU for any sign of rough movement or seizure of the trunnion or center shaft, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-27-60, dated July 12, 2012. (i) If rough movement or seizure of the RFTU trunnion or center shaft is found: Before further flight, replace the RFTU with a new or serviceable RFTU, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-27-60, dated July 12, 2012. (ii) If no rough movement or seizure of the RFTU trunnion or center shaft is found: Before further flight, lubricate the RFTU, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-27-60, dated July 12, 2012. Repeat the lubrication of the RFTU at intervals not to exceed 600 flight hours or 3 months, whichever occurs first, until the RFTU is replaced with a unit that has a serial number outside the affected range or a serial number with a suffix `B.'

This AD was prompted by reports of movement of the rudder pedals being impeded due to corrosion of the trunnion shaft of the RFTU. We are issuing this AD to detect and correct any sign of rough movement or seizure of the trunnion shaft and its bushing, which could cause a rudder control jam or a large and rapid alternating rudder input leading to a structural failure of the vertical fin.

None.