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Flight crew of a british jetstream BA31 experienced the stall warning shaker and stall warning light during climb in light rime ice conditions -- even though the aircraft's speed was above a stall. Subsequent increases in the speed did not totally eliminate the problem until the stall protection system was turned off.
| Attributes | |
| ACN | 386766 |
| Time | |
| Date | 199711 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : fot |
| State Reference | CA |
| Altitude | msl bound lower : 12000 msl bound upper : 12000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa |
| Operator | common carrier : air carrier |
| Make Model Name | Jetstream 31 |
| Operating Under FAR Part | Part 135 |
| Flight Phase | climbout : intermediate altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 280 flight time total : 5600 flight time type : 1400 |
| ASRS Report | 386766 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : critical inflight encounter : weather other anomaly other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
BA3100 jetstream departed acv bound for smf. Aircraft weight was approximately 14000 pounds. Climbing in IMC conditions, the aircraft began to pick up light rime ice (flight was cleared to 17000 ft). At 12000 ft (170 KTS) the right wing stall identify light illuminated, thus triggering the stick shaker. Aircraft pitch attitude was 2-3 degrees pitch up. Stick shaker lasted almost 10 seconds, during which time aircraft ctlability was in question. Aircraft leveled at 12000 ft and accelerated to 190 KTS. Stick shaker came on again momentarily at 190 KTS and again at 200 KTS. The stall system on the BA3100 is controled by 2 rocker switches on the roof panel. After the problem was assessed, the stall protection system was turned off and the flight proceeded to smf and landed without further incident. We were later informed by maintenance that a faulty signal summing unit and stall vane were contributing factors of this scary event.
Original NASA ASRS Text
Title: FLC OF A BRITISH JETSTREAM BA31 EXPERIENCED THE STALL WARNING SHAKER AND STALL WARNING LIGHT DURING CLB IN LIGHT RIME ICE CONDITIONS -- EVEN THOUGH THE ACFT'S SPD WAS ABOVE A STALL. SUBSEQUENT INCREASES IN THE SPD DID NOT TOTALLY ELIMINATE THE PROB UNTIL THE STALL PROTECTION SYS WAS TURNED OFF.
Narrative: BA3100 JETSTREAM DEPARTED ACV BOUND FOR SMF. ACFT WT WAS APPROX 14000 LBS. CLBING IN IMC CONDITIONS, THE ACFT BEGAN TO PICK UP LIGHT RIME ICE (FLT WAS CLRED TO 17000 FT). AT 12000 FT (170 KTS) THE R WING STALL IDENT LIGHT ILLUMINATED, THUS TRIGGERING THE STICK SHAKER. ACFT PITCH ATTITUDE WAS 2-3 DEGS PITCH UP. STICK SHAKER LASTED ALMOST 10 SECONDS, DURING WHICH TIME ACFT CTLABILITY WAS IN QUESTION. ACFT LEVELED AT 12000 FT AND ACCELERATED TO 190 KTS. STICK SHAKER CAME ON AGAIN MOMENTARILY AT 190 KTS AND AGAIN AT 200 KTS. THE STALL SYS ON THE BA3100 IS CTLED BY 2 ROCKER SWITCHES ON THE ROOF PANEL. AFTER THE PROB WAS ASSESSED, THE STALL PROTECTION SYS WAS TURNED OFF AND THE FLT PROCEEDED TO SMF AND LANDED WITHOUT FURTHER INCIDENT. WE WERE LATER INFORMED BY MAINT THAT A FAULTY SIGNAL SUMMING UNIT AND STALL VANE WERE CONTRIBUTING FACTORS OF THIS SCARY EVENT.
Data retrieved from NASA's ASRS site as of July 2007 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.