Pass the Water Buck(et) Downline
By Keith Horton

 

We were experiencing many problems with the water system on the Convair 880 airplanes and we had a project under way in Engineering to find out what was causing all the troubles and get some remedial action going. The following is a copy of a March 1974 letter I prepared for my supervisor’s signature in March, 1964, and sent to a high ranking official in TWA’s New York headquarters:

Subject: Plane 8804 - Water System Problems

This airplane recently experienced a series of difficulties in the water system that resulted in some passenger complaints about lack of water. This letter will advise you of the problem and of our plans to improve the reliability of the water system in the 880 aircraft.

A chronological resume of the events on Plane 8804 is as follows:

On March 16 at Boston a broken plastic line at the water tank was replaced.

On March 16 the same line was replaced at St. Louis

On Flight 193, March 18, the water system low-pressure light came on and Idlewild replaced a plastic line at the water tank.

On Flight 147, March 20, the water system low-pressure light came on during takeoff and the water supply was depleted 15 minutes later. The flight made an unscheduled landing at Detroit because of weather at Chicago. A plastic line above the cargo compartment lining and just forward of the water tank was replaced.

Prior to Flight 147 departure at Detroit, a water line at the top of the tank again pulled out of its end-fitting and the water system was deactivated.  Although a passenger allegedly reported later that there was no liquid service on the flight, the Detroit station personnel said that they had put extra bottles of water on the plane.

When Flight 147 landed at Chicago, the water line was reconnected and the water system was serviced and the flight was dispatched. However, water pressure was lost shortly after departure. Since the system appeared to be operable on dispatch from Chicago, there was no extra liquid service on board and the flight operated dry from Chicago to Phoenix. At Phoenix, they reported that the water system drain valve had not been properly positioned, apparently by the servicing personnel at Chicago.

On the return of Flight 120, March 20, Phoenix to Chicago, the water system was apparently operative, but on the log sheet for this flight, there is the innocuous looking entry “forward lavatory hot water is too hot – passengers complain,” and then there is the following remark by the Flight Engineer, “Disregard – problem is air in tank.”  (This remark and the unfortunately incorrect analysis by the Flight Engineer was the key to the whole problem, to be revealed later.)

On the subsequent layover at Boston, the affected plastic line was replaced, but the airplane operated on Flight 155, March 21, Boston to Denver, with the shut off in the forward lavatory because of water leakage.

The airplane operated Flight 156, March 21, Denver to Boston, and Flight 151, March 22, Boston to Dayton, with the forward lavatory water deactivated.  At Dayton, turnaround Flight 152 incurred a twenty-minute Code 43 delay because the water line filled at the ceiling of the cargo compartment just forward of the water tank.  There was no correction to the water system and the entire system was deactivated.  The delay was incurred in mopping up the water from the cargo floor and fuselage skin.

Maintenance at New York was notified that Flight 152 would arrive (for turnaround to Flight 143) with the water system inoperative and was requested to make every effort possible during the two-hour turnaround to repair the water system.  However, there was insufficient time to make repairs, so two water jugs were placed on board the flight.

On termination of Flight 143 at Los Angeles, Kansas City Engineering was in contact with the Los Angeles Specialty Foremen and it was determined that the forward lavatory hot water tank had been overheating to the point where very hot water (and perhaps steam) had been forced back into the plastic tubing of the water distribution system.  The tubing had been softened by the high temperatures experienced and would continually pull out of the connector.

Overheating of the tank was caused by sticking of one contact of the three-phase water heater control relay switch.

All the plastic distribution lines from the water supply tank to galleys were replaced with copper tubing before further flight of the airplane.  The offending hot water tank and control relay were changed as well.

The log book remark about passengers complaining about the hot water was the signal that should have been received.  We will issue bulletins to both maintenance and flight personnel to acquaint them with the functioning of the heater control circuit and to make them aware that excessively hot water can’t be caused by air in the tank, but is an indication of a failure in the water temperature control circuit.

In review of this experience, you will note that the airplane has been “bouncing” around from one station to another and not until we could stop it at a Technical Services base, could we put the necessary technical and mechanical effort into correcting it.  In order to preclude further incidents of this nature, we have issued a Modification Order to replace the control relays for the forward and aft lavatory hot water heaters on all 880 aircraft on an expedited basis.  This job is expected to be completed by March 30, 1974.  In addition, we are revising the hot water tank control circuitry to install an additional relay to assure positive shutdown of the heater circuit in the event of over-heat of the tank.

You are aware, I am sure, of the continual difficulties that have been experienced with the water distribution system since placing the 880 fleet in service.  Modification Orders have been released to remove the plastic tubing in the galleys and to install copper tubing.  Another Modification Order was released to install sleeves in the ends of the plastic distribution lines to preclude their shrinking and pulling out of the connections.  Modification Order was deferred at last Base Overhaul of the aircraft because of priorities of the A-2 program.  Since Plane #8804 is a former Northwest airplane, this modification has not yet been accomplished. 

At present there are two complete water distribution systems in the aircraft, one for the galley and one for the lavatory.  We cannot maintain these systems with reliability in spite of many modifications, and we are completely removing both systems during the current Base Overhaul cycle and installing a simplified system using a nylon semi-flexible tubing that has been thoroughly tested and investigated.  This same tubing will be installed by Boeing in the 727 aircraft.

The water heater temperature control circuit modification mentioned above will be scheduled for accomplishment during Base Overhaul.  It will be similar to the control circuit that has been quite successful on the 707 aircraft.

This is typical of the kinds of problems we faced there in Engineering.  The airplanes shuttled around from station to station so quickly that often we didn’t learn of a problem until it had been going on for two or three or four days.  Then, after that, it was difficult to get the airplane routed to a place where there were technical people that could help us analyze and repair the problems.

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Keith Horton, 1941-1983, served in Maintenance/Technical Services Engineering and Field Maintenance.