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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Pilot of a C525 reports an uncommanded autoplt disconnect. The reporter states that the space between the trim wheel and yoke is further confined due to the microphone's location. In this particular instance, while in cruise at FL290, this reporter bumped the trim wheel and inadvertently disconnected the autoplt. The aircraft climbed 290 ft above assigned altitude.
| Attributes | |
| ACN | 352878 |
| Time | |
| Date | 199611 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : drk |
| State Reference | AZ |
| Altitude | msl bound lower : 29000 msl bound upper : 29000 |
| Aircraft 1 | |
| Controlling Facilities | artcc : zab |
| Operator | general aviation : personal |
| Make Model Name | Citation I/SP |
| Operating Under FAR Part | Part 91 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other |
| Route In Use | enroute airway : zab |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : private pilot : instrument |
| Experience | flight time last 90 days : 100 flight time total : 1200 flight time type : 100 |
| ASRS Report | 352878 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
Autoplt kicked off by leg rubbing against trim wheel. When tried to stop immediate climb, aircraft went up 250-290 ft from assigned altitude before I could return. Caused by not enough room between control column and trim wheel due to where factory mounts pilot's microphone in new citation jet. Callback conversation with reporter revealed the following information: the autoplt has gone off 3 or 4 times during cruise without any notice. This reporter states that this has happened during a change of heading, radial, or waypoint, too. The fact that the disconnect has occurred is only recognized by the aircraft's climb or descent since the annunciators showing that the autoplt is engaged are not highly visible. One is located down below the pilot seats, on the center console, and the other is on the ehsi, the 'autoplt engine' light extinguishes. Maintenance has not been able to duplicate the problem, but they are looking at the servos. The core autoplt system is the spz-5000 manufactured by honeywell.
Original NASA ASRS Text
Title: PLT OF A C525 RPTS AN UNCOMMANDED AUTOPLT DISCONNECT. THE RPTR STATES THAT THE SPACE BTWN THE TRIM WHEEL AND YOKE IS FURTHER CONFINED DUE TO THE MIKE'S LOCATION. IN THIS PARTICULAR INSTANCE, WHILE IN CRUISE AT FL290, THIS RPTR BUMPED THE TRIM WHEEL AND INADVERTENTLY DISCONNECTED THE AUTOPLT. THE ACFT CLBED 290 FT ABOVE ASSIGNED ALT.
Narrative: AUTOPLT KICKED OFF BY LEG RUBBING AGAINST TRIM WHEEL. WHEN TRIED TO STOP IMMEDIATE CLB, ACFT WENT UP 250-290 FT FROM ASSIGNED ALT BEFORE I COULD RETURN. CAUSED BY NOT ENOUGH ROOM BTWN CTL COLUMN AND TRIM WHEEL DUE TO WHERE FACTORY MOUNTS PLT'S MIKE IN NEW CITATION JET. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE AUTOPLT HAS GONE OFF 3 OR 4 TIMES DURING CRUISE WITHOUT ANY NOTICE. THIS RPTR STATES THAT THIS HAS HAPPENED DURING A CHANGE OF HDG, RADIAL, OR WAYPOINT, TOO. THE FACT THAT THE DISCONNECT HAS OCCURRED IS ONLY RECOGNIZED BY THE ACFT'S CLB OR DSCNT SINCE THE ANNUNCIATORS SHOWING THAT THE AUTOPLT IS ENGAGED ARE NOT HIGHLY VISIBLE. ONE IS LOCATED DOWN BELOW THE PLT SEATS, ON THE CTR CONSOLE, AND THE OTHER IS ON THE EHSI, THE 'AUTOPLT ENG' LIGHT EXTINGUISHES. MAINT HAS NOT BEEN ABLE TO DUPLICATE THE PROB, BUT THEY ARE LOOKING AT THE SERVOS. THE CORE AUTOPLT SYS IS THE SPZ-5000 MANUFACTURED BY HONEYWELL.
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.