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B767 flight crew reports faulty HF radio affecting autopilot in cruise; causing momentary pitch-up when microphone is keyed.
| Attributes | |
| ACN | 773349 |
| Time | |
| Date | 200802 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : cyqm.airport |
| State Reference | NB |
| Altitude | msl single value : 38000 |
| Aircraft 1 | |
| Controlling Facilities | artcc : czqx.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B767-300 and 300 ER |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : relief pilot |
| Experience | flight time last 90 days : 230 flight time total : 9000 flight time type : 7000 |
| ASRS Report | 773349 |
| Events | |
| Anomaly | aircraft equipment problem : less severe |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | other |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
In cruise; center autoplt on. Prior to relieving crew at cruise; outgoing crew reported right HF did not transmit. After they left and myself and other relief pilot took airplane; I tried to couple the HF by turning it off then on. Coupling tone lasted longer than normal and radio subsequently would not couple (frequency was probably 8.864 MHZ). I dialed a different frequency to see if it would work (4.864 MHZ); turned off HF; then on. Upon keying the microphone; airplane jerked nose-up momentarily but quite noticeably; displayed the 'autoplt' caution light on forward panel; then returned to normal. Radio did not couple. We were able to duplicate it one more time under same scenario and decided not to further test the system since it was affecting our flight controls. We informed maintenance of our problem in detail.
Original NASA ASRS Text
Title: B767 FLT CREW REPORTS FAULTY HF RADIO AFFECTING AUTOPILOT IN CRUISE; CAUSING MOMENTARY PITCH-UP WHEN MIKE IS KEYED.
Narrative: IN CRUISE; CTR AUTOPLT ON. PRIOR TO RELIEVING CREW AT CRUISE; OUTGOING CREW RPTED R HF DID NOT XMIT. AFTER THEY LEFT AND MYSELF AND OTHER RELIEF PLT TOOK AIRPLANE; I TRIED TO COUPLE THE HF BY TURNING IT OFF THEN ON. COUPLING TONE LASTED LONGER THAN NORMAL AND RADIO SUBSEQUENTLY WOULD NOT COUPLE (FREQ WAS PROBABLY 8.864 MHZ). I DIALED A DIFFERENT FREQ TO SEE IF IT WOULD WORK (4.864 MHZ); TURNED OFF HF; THEN ON. UPON KEYING THE MIKE; AIRPLANE JERKED NOSE-UP MOMENTARILY BUT QUITE NOTICEABLY; DISPLAYED THE 'AUTOPLT' CAUTION LIGHT ON FORWARD PANEL; THEN RETURNED TO NORMAL. RADIO DID NOT COUPLE. WE WERE ABLE TO DUPLICATE IT ONE MORE TIME UNDER SAME SCENARIO AND DECIDED NOT TO FURTHER TEST THE SYS SINCE IT WAS AFFECTING OUR FLT CTLS. WE INFORMED MAINT OF OUR PROB IN DETAIL.
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.