Flight Crew reported when selecting Flaps Up I heard a loud bang (pop); a TE FLAPS DISAGREE EICAS (no TE Light Illuminated) and Flap Indicator was between Up and 1 after takeoff. The Flight Crew requested vectors and ran the check lists and QRH. After talking with Operations and a SME; the Flight Crew requested priority handling and performed an air turn back and precautionary landing at departure airport.
Synopsis
Flight Crew reported when selecting Flaps Up I heard a loud bang (pop); a TE FLAPS DISAGREE EICAS (no TE Light Illuminated) and Flap Indicator was between Up and 1 after takeoff. The Flight Crew requested vectors and ran the check lists and QRH. After talking with Operations and a SME; the Flight Crew requested priority handling and performed an air turn back and precautionary landing at departure airport.
Narrative
I was the Pilot Flying (PF) during departure. We had flaps 20 and full takeoff thrust selected due to a LLWS Advisory in the ATIS. During climbout; I was hand flying and requested VNAV at 1;000 feet AGL and then requested flaps to 5. Shortly thereafter; I requested the Autopilot to be engaged for the RNAV departure. This was followed in quick succession with Flaps to 1; then Flaps Up; after takeoff checklist; climb 2. At some point after the Flaps Lever was raised to Up; we heard a pop sound and received a TE FLAPS DISAGREE EICAS Message. The Flap Indicator was positioned between Up and 1 with no split. The Autopilot disengaged and I began hand flying the aircraft again. I immediately kept the speed at clean maneuvering (around 200 KIAS) and the Captain (CA) told me to level off at 4;000 feet. The Captain informed ATC that we had a mechanical problem and needed to level off. She also requested vectors to keep us clear of terrain. It was night and we were in and out of clouds with turbulence and rain. ATC began providing vectors and directed a climb to 5;000 feet. During this time; I requested that the Captain re-engage the Autopilot. However; none of the Autopilots would engage. I then realized that the aircraft required a lot of Right Aileron to stay level. I then added about 7 units of right rudder trim to assist. The Captain directed that I continue flying the aircraft as she got into the TRAILING EDGE FLAPS DISAGREE checklist. She ran the checklist until it reached a decision point to continue that checklist; or go to the TRAILING EDGE FLAPS ASYMMETRY checklist. The deciding factor; per the checklist; was whether the TE EDGE light was still illuminated or not. However; we never received a TE EDGE light during the flight and tested the bulb twice to confirm. Due to having noticeable asymmetry in flight; the Captain opted to go to the TE FLAP ASYMMETRY checklist and ran it to the landing section. At this point; the Captain took the aircraft and asked that I review all of the checklists again while she flew. We decided to try engaging the Autopilot again and it did engage; likely due to the trim we had input. Around this time; we also requested priority handling with ATC and then I began running the checklists starting with TE FLAP DISAGREE. After some discussion and the lack of a Trailing Edge Light; I moved the Alternate Flaps Switch from up to 1. This initially appeared to solve the problem as the Flap Indicator was now indicating Flaps 1 and the TE FLAPS DISAGREE EICAS rescinded. However; as I began removing the Rudder Trim for the Captain; she quickly asked that I return the Rudder Trim to 7 units as there was still a noticeable Asymmetry. I returned the Rudder Trim and the Captain asked that I contact Flight Control for further guidance. We also decided to request a holding pattern to continue troubleshooting; which ATC granted. We were unable to contact Flight Control via Jet Comm; so we asked the Local Operations Office to phone patch us to Flight Control and talk over speaker. After establishing contact; we requested to speak to a Subject Matter Expert (SME). After a long discussion of the checklists and our actions up to that point with the SME; we decided to complete the TRAILING EDGE FLAP ASYMMETRY checklist and not to attempt to move the Flaps again. We then requested landing performance data that included the malfunction and to use the longest runway; completed our briefings; and requested vectors to the ILS. ATC was very busy with arrivals and asked if we could accept 15 minutes of vectors. Due to not needing to land immediately; and to burn off more fuel to lighten the aircraft; we accepted the vectors. The Captain took this opportunity to talk about the high speed landing that was required and asked me to read her the section from the Flight Crew Training Manual (FCTM) about landing with a Flap Asymmetry. We were then vectored to and intercepted the ILS. We completed all deferred items remaining in the TRAILING EDGE FLAPS ASYMMETRY checklist. The Captain flew the approach to about 400 feet; then disconnected the Autopilot and landed the aircraft with no issues. After landing; we assessed that the aircraft was safe to taxi back to the ramp. We cleared off the Airport Rescue and Firefighting (ARFF) team; taxied to the ramp and shutdown the aircraft.
Second reporter narrative
The flight was scheduled ZZZ to ZZZ1. The active runway was XXR. LLWS was in the ATIS so I elected to do Flaps 20 with a delayed rotation; maximum thrust take off; engine anti ice on as per the takeoff performance data. LNAV was armed for the ZZZZZ SID. Cleared for takeoff; First Officer (FO) leg. When taxing on to Runway XXR we got an EICAS Left Side Window. Informed ATC; take off clearance canceled; taxied off runway. Did the QRH procedure which cleared the EICAS; also understood a comment write up would be accomplished on the way to ZZZ1. Cleared to take off again Runway XXR. At 1;000 feet FO called for VNAV; Flaps 5; Autopilot Center Command. FO called for Flaps 1; Flaps Up; after takeoff checklist; climb 2. This all came quickly due to the light aircraft and maximum thrust take off. When selecting Flaps Up I heard a loud bang (pop); got a TE FLAPS DISAGREE EICAS (no TE Light Illuminated) and Flap Indicator was between Up and 1. The Autopilot disengaged and the aircraft required approximately 7 to 10 units of Right Rudder Trim to keep wings level. I informed ATC of the flight control malfunction; asked for vectors to work the problem; and requested priority handling. ATC instructed us to climb to 5;000 feet. At this time we were able to re-engage the Autopilot since the aircraft was in trim. The TE FLAP DISAGREE checklist was called for. The FO continued to fly as I worked the checklist. At step 9 of this checklist it states; [to] choose one. So; we had the TE FLAP DISAGREE EICAS still displayed; but no TE Light (never got light just an EICAS). After some discussion exited the checklist and went to the TE FLAP ASYMMETRY checklist as stated to do so in step 9. Once again only the TE FLAP DISAGREE EICAS Message in view at this time. Still holding 7 to 10 units of Right Rudder Trim. Ran the TE FLAP ASYMMETRY checklist up to the check landing data statement. At this point I asked the FO to review the checklist and I would fly the aircraft. Even though we both went threw the checklist initially; the FO was busy flying the aircraft and dealing with airspeed control; turbulence; rain showers; etc.; at that time. The TE FLAP DISAGREE checklist was reviewed first by my FO. After some more discussion about not having the TE Light Illuminated (tested bulbs twice); the Alternate Flap Switch was placed to Flaps 1. The Flap Indicator now showed Flaps 1; however a Rudder Trim of 7 to 10 units was still needed. Left the checklist and decided to call Flight Control and talk to a System Matter Expert (SME). Tried Comms; ZZZ and no luck. Got a hold of ZZZ gateway to relay a message to our Dispatcher; Flight Control; and a SME. During this time we asked for a hold from ATC which was granted. Had a lengthy discussion with the SME about the situation of the aircraft. I decided because of the 7 to 10 units of Right Rudder needed to keep wings level that we had an Asymmetry issue. I did not want to further jeopardize the aircraft's attitude. We ran the TE FLAP ASYMMETRY checklist again to completion. We got the non normal landing data and planned to land Runway XY; Flaps 1 indicated; at ZZZ. The approach was briefed and the deferred items descent; approach; and landing checklists were accomplished. ATC was very busy with arrivals and asked if we could accept 15 minutes of vectors. Due to not needing to land immediately; and to burn off more fuel to lighten the aircraft we accepted vectors. While being vectored for an extended downwind I had my FO pull up the all flap landing information; and landing with an asymmetry in the FCTM (Flight Crew Training Manual) for review. We did the ILS XY coupled to 400 feet; then disconnected the Autopilot and landed. After landing we assessed that the aircraft was safe to taxi to the ramp.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.