 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A320 captain reports low frequency vibrations climbing through FL260 at 320 knots. Vibrations disappear below 290 knots.
| Attributes | |
| ACN | 794920 |
| Time | |
| Date | 200806 |
| Local Time Of Day | 0001 To 0600 |
| Place | |
| Locale Reference | atc facility : zzz.artcc |
| State Reference | US |
| Altitude | msl single value : 26000 |
| Environment | |
| Light | Dawn |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzz.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : vacating altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 794920 |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : unable |
| Consequence | other |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
During climb through approximately 26000 ft at an indicated speed of 320 KTS; aircraft started low frequency (approximately 3-4 oscillations per second); moderate intensity vibrations that felt very much like aerodynamic buffeting. At the time of the encounter; autoplt #1 was engaged. Initially; I selected a slower speed; however; given the intensity of the vibration; I wanted to increase the rate of deceleration. I therefore disconnected the autoplt and increased the aircraft's pitch in order to increase the rate of deceleration. My control inputs did not seem to affect the vibration. The vibration continued until the aircraft slowed to approximately 290 KTS. Once slowed; reengaged the autoplt. The remainder of the flight was normal and uneventful. When I first arrived at the aircraft; I noticed the logbook showed 2 recent write-ups regarding vibration. I assumed the vibration described in these logbook entries were the higher frequency vibrations that have been noted many times on the A320 family of aircraft. The vibration encountered on this flight was much; much more intense and of a much lower frequency. Maintenance is addressing this issue.
Original NASA ASRS Text
Title: A320 CAPT REPORTS LOW FREQUENCY VIBRATIONS CLIMBING THROUGH FL260 AT 320 KNOTS. VIBRATIONS DISAPPEAR BELOW 290 KNOTS.
Narrative: DURING CLB THROUGH APPROX 26000 FT AT AN INDICATED SPD OF 320 KTS; ACFT STARTED LOW FREQ (APPROX 3-4 OSCILLATIONS PER SECOND); MODERATE INTENSITY VIBRATIONS THAT FELT VERY MUCH LIKE AERODYNAMIC BUFFETING. AT THE TIME OF THE ENCOUNTER; AUTOPLT #1 WAS ENGAGED. INITIALLY; I SELECTED A SLOWER SPD; HOWEVER; GIVEN THE INTENSITY OF THE VIBRATION; I WANTED TO INCREASE THE RATE OF DECELERATION. I THEREFORE DISCONNECTED THE AUTOPLT AND INCREASED THE ACFT'S PITCH IN ORDER TO INCREASE THE RATE OF DECELERATION. MY CTL INPUTS DID NOT SEEM TO AFFECT THE VIBRATION. THE VIBRATION CONTINUED UNTIL THE ACFT SLOWED TO APPROX 290 KTS. ONCE SLOWED; REENGAGED THE AUTOPLT. THE REMAINDER OF THE FLT WAS NORMAL AND UNEVENTFUL. WHEN I FIRST ARRIVED AT THE ACFT; I NOTICED THE LOGBOOK SHOWED 2 RECENT WRITE-UPS REGARDING VIBRATION. I ASSUMED THE VIBRATION DESCRIBED IN THESE LOGBOOK ENTRIES WERE THE HIGHER FREQ VIBRATIONS THAT HAVE BEEN NOTED MANY TIMES ON THE A320 FAMILY OF ACFT. THE VIBRATION ENCOUNTERED ON THIS FLT WAS MUCH; MUCH MORE INTENSE AND OF A MUCH LOWER FREQ. MAINT IS ADDRESSING THIS ISSUE.
Data retrieved from NASA's ASRS site as of May 2009 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.