Narrative:

[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 Upon inspection; I could see that the flap actuator was retracted and that the hardware [bolt-nut-cotter key] was still installed in the flap.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.

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Original NASA ASRS Text

Title: 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.

Narrative: [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.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.