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A shop reports that frequency selector panels used on B737-300, B737-500, B757 and B767 aircraft have a design deficiency.
| Attributes | |
| ACN | 522633 |
| Time | |
| Date | 200108 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : maintenance |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : lead technician |
| Qualification | technician : powerplant technician : fcc technician : airframe |
| Experience | maintenance avionics : 35 maintenance lead technician : 14 |
| ASRS Report | 522633 |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other |
| Independent Detector | other other : person 1 |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other Other |
| Factors | |
| Maintenance | contributing factor : engineering procedure performance deficiency : fault isolation performance deficiency : repair performance deficiency : testing |
| Supplementary | |
| Problem Areas | Aircraft Company Maintenance Human Performance |
| Primary Problem | Ambiguous |
Narrative:
VHF communication control head/panel's whole and tenth's megacycle switches are not functioning correctly. Because of a defect, they are switching to another frequency other than the desired, selected frequency. Vibration can cause the control head/switch to change to a different frequency. The direction of rotation of the rotary switches can alter the effect. This does occur on newly installed switches. The collins pin number of the control head is XXX. This pin number is used on at least B737-300, B737-500, B757, and B767 aircraft. This problem has only been seen in this shop since the year 1999. All the support personnel have been notified of this problem and monitoring closely.
Original NASA ASRS Text
Title: A SHOP RPTS THAT FREQ SELECTOR PANELS USED ON B737-300, B737-500, B757 AND B767 ACFT HAVE A DESIGN DEFICIENCY.
Narrative: VHF COM CTL HEAD/PANEL'S WHOLE AND TENTH'S MEGACYCLE SWITCHES ARE NOT FUNCTIONING CORRECTLY. BECAUSE OF A DEFECT, THEY ARE SWITCHING TO ANOTHER FREQ OTHER THAN THE DESIRED, SELECTED FREQ. VIBRATION CAN CAUSE THE CTL HEAD/SWITCH TO CHANGE TO A DIFFERENT FREQ. THE DIRECTION OF ROTATION OF THE ROTARY SWITCHES CAN ALTER THE EFFECT. THIS DOES OCCUR ON NEWLY INSTALLED SWITCHES. THE COLLINS PIN NUMBER OF THE CTL HEAD IS XXX. THIS PIN NUMBER IS USED ON AT LEAST B737-300, B737-500, B757, AND B767 ACFT. THIS PROB HAS ONLY BEEN SEEN IN THIS SHOP SINCE THE YEAR 1999. ALL THE SUPPORT PERSONNEL HAVE BEEN NOTIFIED OF THIS PROB AND MONITORING CLOSELY.
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.