A Lead Line Mechanic reports that five months after he had 'downgraded' the CAT status of an EMB-190 aircraft for a pitch trim control panel change; he was informed that the 'downgrade' was not necessary.
Synopsis
A Lead Line Mechanic reports that five months after he had 'downgraded' the CAT status of an EMB-190 aircraft for a pitch trim control panel change; he was informed that the 'downgrade' was not necessary.
Narrative
I was assisting a Technician on a gate call. An EMB-190 had a pitch trim backup fault message. We troubleshot and replaced a trim control panel. I was in contact with Maintenance Control and since I was not CAT qualified; and there were no CAT qualified technicians available I was told to 'downgrade' the aircraft. I did so under the direction of Maintenance Control. I only made one logbook entry. If this was actually a required 'downgrade'; for the example we had; there would have been three entries required. I was contacted by my Manager; talked to Quality Assurance (QA); and we concurred that the aircraft should never had been 'downgraded.' Reference our procedures manual for CAT critical system repaired immediately with Non-CAT critical component (using logbook example). If there is a logbook discrepancy with any of the CAT critical systems and the problem is immediately repaired by replacing; swapping or re-racking a component that is NOT a CAT critical component and the aircraft is not presently in a 'downgrade' status; the following must occur to keep the aircraft at the Full CAT Status: (a) Complete a satisfactory job card or AMM operational check of the component. The work and logbook signing may be accomplished by our Mechanic or a Maintenance Control Authorized Mechanic. A CAT Certification Test is not required. (b) Installation and rigging/adjustment requirements must be in accordance with Maintenance Manual or job card procedures. (c) Contact Maintenance Control who will review the log page entry and the history of the aircraft back to the date of the last CAT PLA application to ensure there are no open CAT items. (d) The Mechanic will review the logbook to ensure there are no open CAT items not yet entered into teh computer system. (e) The aircraft does not have to be 'downgraded' if there are no open CAT items. (f) One Logbook entry will be made. This entry will state: 1) The name of the component and repair action taken. 2) A satisfactory Operational Check of that component was performed. 3) The aircraft remains at the current CAT status per the examples; including all E190s; 'Per Maintenance Control; Aircraft remains at CAT IIIa Status.' Human factors come into play here. I relied on Maintenance Control for direction and assumed I would be told how to correctly take care of the Logbook. I talked with Quality Assurance (QA) and initiated this report. I also reviewed the procedures manual section as detailed above. Maybe I should have came in from the aircraft and researched the procedure manual for myself. Take time to review reference documentation.
NASA callback
Reporter stated that at the time of the original CAT downgrade status he should have made three entries in the logbook per their procedures manual. Instead he had made only one entry per direction of maintenance control; and that discrepancy was noticed five months later during an audit of the logbook sign-off. Reporter stated that although the horizontal stabilizer is part of the CAT critical system; the trim control panel he replaced in the cockpit center pedestal was considered a Non-CAT critical component per their maintenance procedures and did not require the aircraft CAT status to be downgraded. But they were following maintenance control's instructions to downgrade and defer the EMB-190 because they did not have access to their procedures manual at the gate they were working. Information regarding CAT Critical or CAT associated system components is found in that procedures manual.Reporter stated the trim control panel has the aircraft roll; rudder and a backup stab pitch trim switch on the panel in case the control wheel stab pickle switches fail. The location of the trim control panel near the aft end of the center pedestal makes it susceptible to fluid spills from coffee and drinks; which also contributes to trim control panel failures.Reporter stated the EMB-190 has made greater use of the Honeywell Modular Avionics Unit (MAU) internal card files instead of big black boxes. Part of any Mechanic's concern about trouble shooting and replacing anyone of the card files in the MAU unit is determining what card may; or may not; affect a CAT critical system or CAT critical associated system that may require additional testing prior to releasing the aircraft.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.