Brasilia EMB-120 All Series
Maintenance Powerplant; Maintenance Airframe
Confusion; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Incorrect / Not Installed / Unavailable Part; Human Factors
[Very late in the night] February 2013; in our Air Carrier Maintenance facility; I was installing the right outboard flap on an EMB-120. The flap had been removed by a previous shift to facilitate a sheet-metal repair in the right [engine] nacelle. I mounted the flap to the wing and drove the actuator hydraulically to the 'Down' position to connect it to the flap. The actuator has a rod end with a bearing that sits between two bosses mounted on the flap. It is secured with a bolt; washer; castellated nut and cotter key. On some series of flaps there is a shroud that covers the bosses on the flap. This flap had the shroud. I positioned the tip of the rod end between the bosses and lifted the flap to align the bosses with the rod end; and inserted the bolt. I attempted to displace the flap up and down to verify that the bolt was properly installed. The flap felt secure. I torqued the [castellated] nut and installed the cotter key. I installed the bonding strap that connects the flap to the actuator. I then got the Inspector to look at the installation. After review by the Inspector; we performed the Operational Checks of the flaps. These procedures were performed in compliance with the Flap Installation Card 27-000-XXXX and in reference to the Aircraft Maintenance Manual Chapter 27-50-04. After completing the paperwork; I ended shift [approximately] 45-minutes later. Late afternoon the next day; I was asked to go retrieve a plane from the gate that was coming offline for what I was told was a steering issue. The aircraft was [the EMB-120]. When I arrived at the gate; the Captain informed me that the problem was instead a 'roll' issue. He had 'returned to the field' after experiencing an abnormal roll characteristic that increased with speed. After talking to the Captain; I walked around the plane to the right side because I knew that all three right flaps had been removed the day before. The right outboard flap was fully extended. All other flaps were fully retracted. Upon inspection; I could see that the flap actuator was retracted and that the hardware [bolt-nut-cotter key] was still installed in the flap. Apparently; when connecting the actuator to the flap; the rod end was past the bosses [on the flap] and rode on the shoulder of the rod end. In this position; it felt secure because it was wedged in between the bolt and the shroud. In the air; however; the air loads must have forced it down. In the past year there has been considerable amount of emphasis placed on combating complacency; both by the FAA and by our Air Carrier. As an Airframe/Powerplant (A & P) for 20 years; that has taken great pride in my work and embraced the responsibility that comes with working on airliners; it was almost offensive to think that I could be complacent. But after a thoughtful evaluation of my performance in the incident; I can reach no other conclusion. I know that the Force Check that I performed of the attachment of the actuator was not sufficient. I should have taken the extra time to get a mirror and a flashlight to see inside the shroud and visually verify that the bolt was in the correct position. I am so thankful that the Captain had sufficient aileron to overcome the extra lift generated by that extended flap. Upon arrival back at the hangar; I informed my Supervisor and the Inspector. The Inspector in turn notified Maintenance Control. I think that the training and emphasis that has been on combating complacency must continue. Mechanics are prideful. It is both a positive and negative attribute. They need to take pride in their work; but not so much that they think they can't make a mistake. Complacency [resulted in] air turn-back.
EMB-120 aircraft in for Routine Overnight Check (RON) for flap sheet metal repair on right wing. All three flaps were removed to facilitate maintenance. After sheet metal repair was completed; all three right side flaps were re-installed per Aircraft Maintenance Manual and Work Cards and signed-off. During right outboard flap actuator to right outboard flap surface bolt installation; flap actuator rod-end not lined up with eyelets on flap surface; yet bolt was able to be installed and safetied. Attach point is shrouded [from] visual check of safeties. I also physically moved the flap to verify that the actuator is connected to the flap. After this step; Travel Checks and Operational Checks are completed with no defects noted. Flaps [were] then being left at 45-degree setting to finish other maintenance on aircraft.Pilot returned to field after aircraft rolled after takeoff. Aircraft grounded; Maintenance Control notified and safety notified; as well as immediate Supervisors. I will have to change the angle of my Visual Inspection of the flap actuator to flap surface bolt connection when dealing with shrouded outboard flap attach points to verify positive engagement; as physically moving the flap surface is not enough to ensure proper operation.
An Aircraft Maintenance Technician and an Inspector report about an EMB-120 aircraft that 'returned to field' after pilot experienced an abnormal 'roll' characteristic after they had signed-off a right outboard flap installation and Operational Check.