Maintenance Airframe; Maintenance Powerplant
Maintenance Inspector 5; Maintenance Technician 15
Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Procedure; Manuals; Human Factors; Chart Or Publication
The Maintenance Release arrived from a Cessna Vendor in ZZZ1. I was assigned the [completed] Work Package for review. When reading the pilot write-up; the [Elevator Trim] actuators were lubed and the Trim System passed the Functional Check. The Cessna [Maintenance] Discrepancy states that after running the system several times; some resistance was felt. It was determined by Cessna that the actuators needed lubed so they [lubed] them and noted that the grease pushed out during the lube indicated contamination. [The Cessna Vendor] did not say if it was with water; or an inappropriate type of grease. After the lube; the system was run several times and the Functional Test was within specs; referencing [the Cessna] 560XL Maintenance Manual (M/M) 27-37-04; so I released the aircraft.  I was made aware of a problem with the ZZZ1 Cessna [Vendor's] maintenance when I arrived at work [the following] day at XA:00pm and filed this report. [Recommend] if we would like to have components replaced if contamination is found; we may want to add that statement to the discrepancy.  We could develop a Checklist for Maintenance Control to review with the Vendor to ensure the system was troubleshot; not just a small portion of the system looked at; before the work is started and before the Maintenance Release is submitted for Return To Service (RTS).  The Director of Maintenance (DOM) approved the release [of the CE-560XL aircraft] for frozen or restricted flight controls.
Reporter stated he is part of his organization's Quality Control and oversees parts removal and replacements accomplished by Contract Maintenance Vendors. Some of their Cessna CE-560s are occasionally parked outside for four or five days in cold weather and the grease in the Elevator Trim Actuator in the tail section thickens and draws moisture. That moisture tends to freeze and either locks-up the Trim Actuator; or makes the cockpit Elevator Trim mechanical thumbwheel difficult to move. The grease in the Trim Actuator gearbox is generally the problem area.Reporter stated the original discrepancy written-up by the Flight crew described an Elevator Trim problem in flight. At the time; his company did not believe they had a replacement actuator in stock. So the Cessna Contract Vendor pumped new grease into the Elevator Trim Actuator; purging the old grease out; performing a Functional Check of the Trim Actuator per the Cessna Manual which describes that procedure as acceptable for a maintenance sign-off for that type of discrepancy. The aircraft was then given a Maintenance Release by the Vendor.Report stated that in the meantime; a Serviceable Elevator Trim Actuator had been located in-house and sent to the Contract Vendor after the Vendor had signed-off the Maintenance Release. The CE-560XL was still at the Vendor and had not yet departed. Because of the known concern about the Elevator Trim issue; his organization prefers to replace the Trim Actuators.  The Vendor was notified to change the actuator. When the Vendor Maintenance personnel re-opened the tail section; they also found one of the Trim cables had completely 'Bird-caged;' (Bird-nested) [cable strands separated] at the Trim Actuator. 'How' and 'Why' the Trim cable condition was missed when the Vendor mechanics purged the Trim actuator grease has not been resolved. Questions about what was actually checked prior to the Maintenance Release being siged-off has become an issue.
A Quality Control Representative for a Part 135 Operator describes the maintenance practices of a Contract Maintenance Vendor and the events surrounding a questionable Maintenance Release sign-off of one of their CE-560XL aircraft.  The Elevator Trim Actuator had previously frozen in flight.