Maintenance of primary flight control surface power actuators is generally beyond the capability of organizational maintenance-level activities. Removal of hydraulic components and associated linkages on the power actuators will destroy critical adjustments. Readjustment requires special tooling, jigs, and other equipment available only at intermediate- or depot-level maintenance facilities. When a power mechanism has been isolated as the cause for flight system malfunction, it is removed. It is forwarded with the accompanying paperwork to the supply activity for disposition.

There have been many cases reported in which, after flight, pilots have found flight controls jammed while the aircraft was on the ground. Because the controls were freed by excessive pressure before an inspection could be made, the causes for the jammed condition could not be found. No positive corrective action was taken before the aircraft were released for flight. In some cases, accidents occurred on such aircraft shortly thereafter.

When an aircraft experiences a control discrepancy during flight, a thorough investigation should be conducted immediately. In cases where aircraft have safely returned from a flight during which a control discrepancy was experienced, a thorough investigation is necessary. This investi-gation must be made before further flight. All parts of the affected control system should be inspected for proper rigging, clearances, and potential causes for interferences. All sealed units that are suspect must be replaced. Primary cause factors that should not be overlooked include maneuvers that have exceeded the operational design of the control systems. Hydraulic system contamination, corrosion and/or distorted or disconnected linkage may have caused the problem. Inadequate lubrication and external contamination in the form of preservative compounds, such as grease combined with dirt and dust, may have caused the problem. An increasing number of flight control system malfunctions are related to system contami-nation, and this ever-important aspect of hydraulic system maintenance should be given the attention it deserves. Checking of system filters and con-tamination inspection of suspected systems are within the capability of organizational activities. If a system is found to be contaminated, the source of contamination must be eliminated and the system cleaned by recycling or flushing in accordance with instructions provided in the appropriate MIM.

Contaminated components must be replaced as necessary to restore proper system operation. Disposition instructions for removed hydraulic components vary with the production status of the aircraft model. Diligent care must be taken to retain the component in the as-is condition, with no change in adjustment, disassembly, or cleaning. If the component has slides or pistons that are jammed, no attempt to free them should be made. 

The aircraft must not be released for further flight until the cause has been determined and corrected. If it is not readily apparent why the component malfunctioned, you should submit a Hazardous Material Report/Engineering Investigation request. If the discrepancy cannot be duplicated or cause determined, an appropriate entry must be made in the Miscellaneous History section of the aircraft logbook.