Narrative:

We configured normally for a VMC approach. I called for the landing checklist at 1500' AGL. As the first officer read the checklist; I noted the flap gauge showed the flaps at 10 degrees although flaps 30 was selected. I performed a normal go-around. There was no asymmetry or roll that might be associated with a spindle failure. We checked for a popped flap gauge circuit breaker. I felt we might have a gauge problem as the aircraft performed as if the flaps were down normally. We reconfigured on downwind; stopping at flaps 15; but again the flap gauge stopped at position 10. The lights on the overhead console showed that the te flaps and le devices were extended. The circuit breaker remained in; so we proceeded with the flaps; trailing edge: symmetrical non-normal/no flaps checklist. As the first officer read through the first several steps and the multiple notes; warnings; and cautions; I became more convinced this was not the problem we had. Since the flaps were symmetric; the lever was at position 15; we were down to 4300 pounds of fuel; and I suspected a gauge problem; I decided to stop trouble shooting and get the aircraft on the ground. I had dispatch on the radio (I had asked them previously to try to get maintenance up so we could ask about the possibility of a malfunctioning flap gauge). I told dispatch I was going back to the airport and land with flaps 15. The first officer and dispatch agreed and we ran the performance data showing about a 2500' stopping margin. We landed uneventfully. No emergency was declared. The obvious question is why did I use flaps 15 landing data when the flap gauge showed flaps 10? There were two reasons. First; I mistakenly thought there was a gauge problem. Second; step 1 of the checklist says; 'flap lever....15 detent' which is where we were. There is also a lengthy caution associated with that step about asymmetry concerns when using the alternate flap system. The checklist gets more confusing when it discusses the use of the alternate flap switch in steps 2 and 3 and references a long note in box 1. Given our 4300 pounds of remaining fuel; the fact that the airplane was handling well with the current configuration; and I did not know the approach speed for a flaps 10 approach; I determined that I would fly a flaps 15 approach and add five to seven knots on final until the last several hundred feet. The approach was stable; the landing was very smooth; and braking and roll out were normal. I did not realize until reviewing configuration speeds on the performance data afterwards that there is a toggle for 'flaps greater than 1; but less than 15.' had I known that; I would have selected that for our approach data. Also; after step 3 in the checklist; we chose the left side of the procedures; 'te flaps operate with no asymmetry.' in retrospect; we could have chosen the right side; 'te flaps do not operate or an asymmetry develops' (which is not the indications we had; but would have given us the proper airspeed to fly on final). I have worked through the QRH checklist for flap problems several times in the simulator and I've reviewed it every year preparing for pcs; however; this is the first time I've actually had to use it in flight. As the above dialog points out; I was confused by the indications I had; the aircraft performance; and the rambling and ambiguous checklist procedures. There are three basic steps with two extensive notes on the opposite page. Following those steps are two options; each containing six more steps with three and four notes included. Had we proceeded with those steps; we would have gotten the left side flaps to 15 degrees; but the right side had a broken actuator connector; and it would have never extended beyond 10 degrees. Thus; we would have created an asymmetry; and; by then; only have had 3500-3000 pounds of fuel. Sitting at my desk and studying the QRH for over 45 minutes; I can better understand the logic of the QRH; although the wording is confusing. Had I performed steps 4 through 9 on the right side; I would have had the proper approach speed for a flaps 10 approach; however; since our te flaps operated; the checklist does not lead to those steps. This is misleading and needs correction.

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Original NASA ASRS Text

Title: A B737-300 right flap actuator connect failed preventing the flaps from extending beyond Flaps 10. The crew found the QRH procedure confusing and ultimately landed at Flaps 10 using Flaps 15 Ref speeds.

Narrative: We configured normally for a VMC approach. I called for the Landing Checklist at 1500' AGL. As the First Officer read the checklist; I noted the flap gauge showed the flaps at 10 degrees although flaps 30 was selected. I performed a normal go-around. There was no asymmetry or roll that might be associated with a spindle failure. We checked for a popped flap gauge circuit breaker. I felt we might have a gauge problem as the aircraft performed as if the flaps were down normally. We reconfigured on downwind; stopping at flaps 15; but again the flap gauge stopped at position 10. The lights on the overhead console showed that the TE flaps and LE devices were extended. The circuit breaker remained in; so we proceeded with the Flaps; Trailing Edge: Symmetrical Non-normal/No Flaps Checklist. As the First Officer read through the first several steps and the multiple notes; warnings; and cautions; I became more convinced this was not the problem we had. Since the flaps were symmetric; the lever was at position 15; we were down to 4300 pounds of fuel; and I suspected a gauge problem; I decided to stop trouble shooting and get the aircraft on the ground. I had Dispatch on the radio (I had asked them previously to try to get Maintenance up so we could ask about the possibility of a malfunctioning flap gauge). I told Dispatch I was going back to the airport and land with flaps 15. The First Officer and Dispatch agreed and we ran the performance data showing about a 2500' stopping margin. We landed uneventfully. No emergency was declared. The obvious question is why did I use flaps 15 landing data when the flap gauge showed flaps 10? There were two reasons. First; I mistakenly thought there was a gauge problem. Second; step 1 of the checklist says; 'Flap Lever....15 Detent' which is where we were. There is also a lengthy caution associated with that step about asymmetry concerns when using the alternate flap system. The checklist gets more confusing when it discusses the use of the alternate flap switch in steps 2 and 3 and references a long note in box 1. Given our 4300 pounds of remaining fuel; the fact that the airplane was handling well with the current configuration; and I did not know the approach speed for a flaps 10 approach; I determined that I would fly a flaps 15 approach and add five to seven knots on final until the last several hundred feet. The approach was stable; the landing was very smooth; and braking and roll out were normal. I did not realize until reviewing configuration speeds on the performance data afterwards that there is a toggle for 'Flaps greater than 1; but less than 15.' Had I known that; I would have selected that for our approach data. Also; after step 3 in the checklist; we chose the left side of the procedures; 'TE flaps operate with no asymmetry.' In retrospect; we could have chosen the right side; 'TE flaps do not operate or an asymmetry develops' (which is not the indications we had; but would have given us the proper airspeed to fly on final). I have worked through the QRH checklist for flap problems several times in the simulator and I've reviewed it every year preparing for PCs; however; this is the first time I've actually had to use it in flight. As the above dialog points out; I was confused by the indications I had; the aircraft performance; and the rambling and ambiguous checklist procedures. There are three basic steps with two extensive notes on the opposite page. Following those steps are two options; each containing six more steps with three and four notes included. Had we proceeded with those steps; we would have gotten the left side flaps to 15 degrees; but the right side had a broken actuator connector; and it would have never extended beyond 10 degrees. Thus; we would have created an asymmetry; and; by then; only have had 3500-3000 pounds of fuel. Sitting at my desk and studying the QRH for over 45 minutes; I can better understand the logic of the QRH; although the wording is confusing. Had I performed steps 4 through 9 on the right side; I would have had the proper approach speed for a flaps 10 approach; however; since our TE flaps operated; the checklist does not lead to those steps. This is misleading and needs correction.

Data retrieved from NASA's ASRS site as of April 2012 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.