Date: 201403
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Light: Night
Aircraft: Citation V/Ultra/Encore (C560)
Operator: Fractional
Aircraft component: Emergency Exit
Component problem: Malfunctioning
Reporter organization: Fractional
Reporter function: Technician
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Communication Breakdown
Second reporter function: Lead Technician
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Other During Maintenance
Result: Aircraft Aircraft Damaged; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Chart Or Publication; Human Factors; Manuals; Procedure
Primary problem: Human Factors

Narrative: A Cessna C-560 aircraft came in for Overnight inspection.  An MEL on a right-hand window shade required sidewall and Emergency Exit to be removed for access to [the window] shade. Emergency Exit could not be removed. Exit had to be removed by two people; one on the inside pulling and one on the outside pounding. This has happened numerous times with the C-560 aircraft.  The Emergency Exit requires a shim seal to be made from sealant.  It appears that the shim seal was not fully cured before Exit door installation. [Recommend] the maintenance procedure for making the [shim] seal for the Exit needs to be checked.  Should we be checking the operation of the Emergency Exit during visits at ZZZ?  Emergency Exit unable to open.

Callback: Reporter stated he was referring to their Cessna 560 Encore aircraft that are being found with Emergency Exit doors stuck in the closed position. The Emergency Exit uses a plug type door that sits in the bottom of the door frame cutout and falls inward; when the upper latch handle is released. He suspects the faying sealant may seem 'cured' to the touch; but has not fully set-up in the middle of the sealant. If the Exit door is installed with the sealant in that condition; there is a strong suspicion the sealant bonds to the flat rubber seal on the Exit door after door installation.Reporter stated there was a huge problem several years ago with the Emergency Exit doors found 'glued' in the closed position on Cessna-560 Ultra aircraft. A check of their Ultra aircraft; identified some had the Exit doors 'glued' shut and unusable. He suspects the current and on-going similar problems with their 560-Encore aircraft may be occurring during the aircraft's 1200 Hour Inspection Checks. The Cessna 560 XL Emergency Exit is aft of the right wing; just forward of the Right Engine. That Exit door uses a bulb type seal on the door and so far they have not seen any Exit doors that have been found stuck in the closed position; at least none that he knows about currently.

Second narrative: While performing maintenance on a Cessna C-560 aircraft; we needed to remove the Emergency Exit door to gain access to [get] behind the sidewall interior panel. Unable remove the Emergency Exit door; even with one technician attempting to open the door from the inside; and another pushing and pounding on the outside frame. Fabricated tooling to allow removal of door. [Recommend to] investigate for possible degradation of rubber seal which may bond the door frame to the door opening structure. Investigate Vendors or Manufacturer for possible incomplete cure of fay/shim seal before the installation of the Emergency Exit door. Investigate if parting agent is proper material for this installation configuration.  Note: this is a recurring defect on this airframe. Flight delay. Stuck Emergency Exit Door.

Second callback: Reporter stated he is a Lead Mechanic with numerous years experience on Cessna aircraft. The faying sealant is used to smooth out the surface of the fuselage frame cutout where the Emergency Exit Door is installed. The flat seal on the Exit door is made of a neoprene material; approximately 1/16'th of an inch thick; that is used to take up the smaller gaps in the mating surface between the Exit door frame surface and the fuselage frame structural cutout. There have been very few pressurization problems with the Exit door design. But finding the same Exit doors stuck closed; unable to be opened; even with two people; has been a real concern for some time. Reporter stated the application of petroleum jelly as a parting agent on the flat seal of the Exit door may be contributing to a chemical interaction with the sealant and flat seal. Especially if the sealant has not fully cured because maintenance procedures were not followed for the required 'cure' time; or the aircraft's external skin is exposed to excessive heat from hot outside environments. The petroleum jelly is used to help 'part'; to help separate; the Exit door flat seal from the fuselage faying sealant surface during the door rigging and fit procedures. He does not know if there is a Job Card requiring removal of the parting agent (petroleum jelly) from the flat seal prior to final reinstallation of the Exit door; after certain Maintenance Checks are completed. The Maintenance C-Checks and Heavy Maintenance Visits for their Cessna-560 encores are contracted out to outside Repair Stations.

Synopsis: Two aircraft maintenance technicians (AMTs) report an Emergency Exit door on a company Cessna C-560 aircraft was found stuck in the closed position during routine maintenance. Exit Door could not be removed or opened; even with one Technician pulling the door from inside and another Technician pounding on the outside frame. Both technicians note the stuck Exit door is a recurring issue on the C-560 Encore airframe.