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An airbus 320 in cruise at FL310 descended below assigned altitude while troubleshooting an autobrake problem. Maintenance request to extend gear exceeded fom limits.
| Attributes | |
| ACN | 504026 |
| Time | |
| Date | 200102 |
| Day | Tue |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : blh.airport |
| State Reference | CA |
| Altitude | msl single value : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zla.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : level |
| Route In Use | enroute airway : j50.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 27 flight time total : 19500 flight time type : 27 |
| ASRS Report | 504026 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : commercial pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude maintenance problem : improper maintenance non adherence : published procedure non adherence : far |
| Independent Detector | aircraft equipment other aircraft equipment : autobrake light other flight crewa other flight crewb |
| Resolutory Action | aircraft : automation overrode flight crew flight crew : returned to assigned altitude |
| Consequence | other other |
| Factors | |
| Maintenance | performance deficiency : fault isolation performance deficiency : non compliance with legal requirements |
| Supplementary | |
| Problem Areas | Maintenance Human Performance Environmental Factor Chart Or Publication Aircraft Flight Crew Human Performance |
| Primary Problem | Maintenance Human Performance |
Narrative:
After leveloff at FL310, first officer noticed that autobrake maximum (rejected takeoff) light still illuminated. Should have gone out automatically after airborne for 10 seconds. Had first officer contact our maintenance control for advisement. Maintenance wanted us to cycle landing gear (extend and retract) to see if light would extinguish. I slowed aircraft to 220 KIAS which is good for vlo extension and retraction. With autoplt on, I had first officer extend landing gear. As gear doors opened and gear extended, aircraft ballooned and climbed to approximately FL311.5. Autoplt returned aircraft to FL310. I then had first officer retract landing gear and as gear doors opened and gear came up, the aircraft began descent. I monitored as autoplt corrected up and autothrust applied power. However, the descent was not arrested and reversed until approximately FL306.5. Before we did this procedure, we advised ZLA we would be slowing and cycling landing gear. This procedure did not take care of our light problem. However, we did determine that autobrakes were off by ECAM (wheels display). What had my first officer and I baffled is why the aircraft descended 350 ft while we retracted the landing gear. Since this was my first trip off of IOE and my first officer being relatively new to the aircraft (4 months since checking out), we decided to look in the aircraft fom for clues. We found it. Maximum altitude for landing gear operation is FL250. While we had complied with the speed for operating the gear, we had both forgotten the operating altitude.
Original NASA ASRS Text
Title: AN AIRBUS 320 IN CRUISE AT FL310 DSNDED BELOW ASSIGNED ALT WHILE TROUBLESHOOTING AN AUTOBRAKE PROB. MAINT REQUEST TO EXTEND GEAR EXCEEDED FOM LIMITS.
Narrative: AFTER LEVELOFF AT FL310, FO NOTICED THAT AUTOBRAKE MAX (REJECTED TKOF) LIGHT STILL ILLUMINATED. SHOULD HAVE GONE OUT AUTOMATICALLY AFTER AIRBORNE FOR 10 SECONDS. HAD FO CONTACT OUR MAINT CTL FOR ADVISEMENT. MAINT WANTED US TO CYCLE LNDG GEAR (EXTEND AND RETRACT) TO SEE IF LIGHT WOULD EXTINGUISH. I SLOWED ACFT TO 220 KIAS WHICH IS GOOD FOR VLO EXTENSION AND RETRACTION. WITH AUTOPLT ON, I HAD FO EXTEND LNDG GEAR. AS GEAR DOORS OPENED AND GEAR EXTENDED, ACFT BALLOONED AND CLBED TO APPROX FL311.5. AUTOPLT RETURNED ACFT TO FL310. I THEN HAD FO RETRACT LNDG GEAR AND AS GEAR DOORS OPENED AND GEAR CAME UP, THE ACFT BEGAN DSCNT. I MONITORED AS AUTOPLT CORRECTED UP AND AUTOTHRUST APPLIED PWR. HOWEVER, THE DSCNT WAS NOT ARRESTED AND REVERSED UNTIL APPROX FL306.5. BEFORE WE DID THIS PROC, WE ADVISED ZLA WE WOULD BE SLOWING AND CYCLING LNDG GEAR. THIS PROC DID NOT TAKE CARE OF OUR LIGHT PROB. HOWEVER, WE DID DETERMINE THAT AUTOBRAKES WERE OFF BY ECAM (WHEELS DISPLAY). WHAT HAD MY FO AND I BAFFLED IS WHY THE ACFT DSNDED 350 FT WHILE WE RETRACTED THE LNDG GEAR. SINCE THIS WAS MY FIRST TRIP OFF OF IOE AND MY FO BEING RELATIVELY NEW TO THE ACFT (4 MONTHS SINCE CHKING OUT), WE DECIDED TO LOOK IN THE ACFT FOM FOR CLUES. WE FOUND IT. MAX ALT FOR LNDG GEAR OP IS FL250. WHILE WE HAD COMPLIED WITH THE SPD FOR OPERATING THE GEAR, WE HAD BOTH FORGOTTEN THE OPERATING ALT.
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.