B737-700
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 120; Flight Crew Type 8000
Troubleshooting; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft
On rotation; the Takeoff Warning horn sounded and an amber LE Flaps Transit light illuminated. The horn stopped once we got airborne. We left the flaps at 1 and leveled off at 8000' and 210 knots to work the QRH. The Leading Edge Flaps Transit procedure decision tree did not fit our exact situation. The first choice was definitely not correct; but the second and third did not exactly fit out situation which was on takeoff; flaps extended. We chose the third option because it seemed the closest to our problem. It led us to 'roll is encountered'. This aircraft didn't fly straight to begin with. I had made a comment to the Captain two legs prior; that it was hard to trim. I detected no roll so we continued which led us to a speed restriction of 300/.65 and a flaps 15 landing. It turned out we had a Number 4 Slat Hydraulic Control fail and it was hanging out the whole flight. Judging by the damage to the fairings on the slat; I don't think we should have flown greater than 230 knots but the QRH lead us to believe we could. We didn't encounter any roll because all the slats were still out when we reached that point in the checklist. After that point; I used the autopilot; and when we got to Step 3 in the checklist; all slats; but number 4 retracted; unknown to us. I only got roll when I disconnected the autopilot for landing. What I'm trying to express is that the second choice in the decision tree; and if roll is encountered on the third choice both keep the speed below 230 knots; but due to us being unsure which situation fit we ended up on the part that allowed us to increase airspeed. I'm not sure this was correct. The second issue was on landing we were expecting a flaps 15 landing with slats and TE [trailing edge] flaps. The slats didn't extend on approach. We were concerned about not having the right REF Speeds so we went around and consulted the QRH. There is no mention of the slat position for landing in the checklist. A note in the QRH stating the REF Speed is for slats out or in would have eliminated our confusion.
A Boeing 737 pilot reported experiencing a Leading Edge Slat anomaly just as the aircraft was being rotated for takeoff.