Flight Crew Last 90 Days 215; Flight Crew Type 5500
Situational Awareness; Human-Machine Interface; Confusion; Communication Breakdown; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Flight Crew Diverted; General Maintenance Action
Aircraft; Human Factors
On approach our yaw damper failed. The Captain elected to attempt to reset the yaw damper; but his attempts were unsuccessful. After being distracted by the yaw damper malfunction; we continued to configure for the approach. However; we were unable to stabilize the aircraft by 1;000 AGL as required by company policy; therefore; I called for a go-around. The Captain concurred; and we executed a missed approach.During the approach; I had noticed abnormal indications on the MASI. Specifically; the low speed red checkerboard and low speed yellow tape indications were displaying at much higher airspeeds than normal. I mentioned this to the Captain; but he disregarded it and immediately began to prepare for another approach. On the second approach; the same abnormally high MASI indications occurred. Since we were not able to achieve a stabilized approach; I called for another go-around. The Captain again concurred and we executed a second missed approach. I suggested that we get delaying vectors in order to run the Yaw Damper Failure Abnormal Checklist since I suspected that abnormal MASI indications may in some way be related to the failure of the yaw damper. The Captain concurred and we ran the Yaw Dampener Failure Abnormal Checklist. Because this did not correct the abnormally high low speed indications on the MASI; we contacted Company Maintenance via the radio in an attempt to gain help in sorting out the problem. Maintenance was unable to offer advice. However; moments later; I noticed that the flaps had failed to retract fully. This led me to make the correct diagnosis of a flap failure. We completed the no-Flaps Abnormal Checklist and diverted.I should have been more assertive by insisting that we get delaying vectors in order to diagnose the abnormally high low speed indications on the MASI after the first missed approach. I unwisely let the Captain rush me into immediately beginning to prepare for a second approach rather than insisting that we get delaying vectors to slowly and methodically diagnose the problem. I believe that we both initially (and hastily) dismissed the abnormal indications as a temporary software glitch. The abnormal MASI indications also distracted our attention from the flap position indicator.
The reporter advised they ultimately determined the flap position indicator showed the flaps were extended somewhere between zero and one. He felt confident they had been at that setting throughout the event. He emphasized the crew's failure to specifically check the flap indication was in part the result of their preoccupation with the yaw damper failure for which they hadn't initially conducted the appropriate checklist and the abnormal MASI indications for which they were trying to somehow logically relate to the failed yaw damper.When asked about flap fail/asymmetry warning lights/aural warnings he stated that there are none on the 737 models in their fleets. He was; in fact; aware that at least one company flight crew had flown an entire approach with the flaps at zero with the flap handle in an 'appropriate' landing setting and that the lack of any unique warning for such a failure he believes it is likely to happen again (and; he noted; probably had).When asked about deviations from normal control input effects from flap extension/retraction cycles he advised he was not the pilot flying and could not remember whether the captain was hand flying or on autopilot. On that subject he believes that the 737 models with which he is familiar exhibit less attitude change or positive/negative seat of the pants G forces than other types when flaps are extended or retracted. He did not recall any evident and/or significantly different such changes during the episode.Upon arrival at their diversion airport the flaps were extended using the alternate; electrical system.
When their yaw damper failed on approach the flight crew of a B737-700 was distracted and; unable to establish a stabilized approach to the short runway at their destination; performed a missed approach. A second approach suffered the same inability to stabilize at which time the First Officer noted abnormally high 'low speed' stall indications on the MASI [Mach Air Speed Indicator] and realized the flaps had not extended as commanded. They diverted successfully to an airport with longer runways.