# SDR 2007UALA01512

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 15, 2007
- Submitted: May 18, 2007
- Operation: Air carrier
- Aircraft: [N182UA](https://openairdocs.org/aircraft/N182UA), registered now
- Make and model: Boeing 747422
- Aircraft serial: 25279
- Aircraft time: 68,301 hours, 8,449 cycles
- Engine: Pwa PW4056
- System (JASC): [3830 · Waste Disposal System](https://openairdocs.org/jasc/3830)
- Part: Lavatory
- Condition: Inoperative
- Location: Cabin
- Stage of operation: CR
- How discovered: O
- Nature of condition: W
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2007UALA01512

## Discrepancy

FLIGHT DIVERTED DUE TO ALL LAVATORIES GOING INOP.  HISSING SOUND NOTED BELOW 1R.  TRIED TROUBLESHOOTING TO NO AVAIL.  [SUP 06-06-07]  EXISTING SERVICE BULLETIN 747-38-2109 DIRECTS TO REPLACE RELAY R8432 (LEVEL SENSING TRANSFER RELAY). THIS RELAY IS IDENTIFIED AS THE SINGLE POINT FAILURE WHICH CAUSES ALL 4 WASTE TANK CONTROLLERS TO LOSE PWR.  REPLACED RELAY. A/C RETURNED TO SERVICE WITH NO REPEAT OF PROBLEM.

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