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--- projects:challenger604:drainmast [2019/09/27 04:09]
dwheele [Captain's Circuit Break Blown]
+++ projects:challenger604:drainmast [2019/09/27 04:22] (current)
dwheele
@@ Line 1: / Line 1: @@
 ====== Heated Drain Mast ======
-On the Challenger 604, the forward Drain Mast heater is electrically open. The symptoms reported by the crew are that the circuit breaker keeps popping. Perhaps this is caused by an electrical wire internal to the heater shorting to ground.
+On the Challenger 604, the crew reported that the Drain/Line Heater circuit breaker in the Galley keeps popping when in the air.
+We measured the forward Drain Mast heater and discovered that it is electrically open.
 ^Heated Drain Mast|115677-114|Electrofilm Mfg. Inc.|
@@ Line 23: / Line 25: @@
 **Galley Circuit Breakers**
-The relevant circuit breaker for the Drain/Line Heater is mounted to the front in the same way as the others, and the output wire travels to the back via J22 (J25 is visible). Tracing the route of this wire was difficult. Found that it went to the relay panel located behind the Ice Box.
+There is a panel of circuit breakers located to the forward part of the upper galley. The relevant circuit breaker for the Drain/Line Heater is mounted to the front in the same way as the others, and the output wire travels to the back via J22 (J25 is visible). Tracing the route of this wire was difficult. Found that it went to the relay panel located behind the Ice Box.
 {{:projects:challenger604:galleycircuitbreakers.jpg?direct&400|Galley Circuit Breakers}}
 ===== Solution =====
-Discovered that there was a line heater for the Water Valve (FILL SOLENOID, see schematic below), located in the cargo hold area, right side, that was shorted against a bolt. Severe charring was present.
+After multiple troubleshooting steps, discovered that there was a line heater for the Water Valve (FILL SOLENOID, see schematic below), located in the cargo hold area, right side, that was shorted against a bolt. Severe charring was present.
+For the aircraft to be flyable, awaiting the acquisition of a replacement line heater, we disconnected the lead going to the line heater, and also clipped that wire near the point it connected to the heater, and removed the line heater. Tied back the lead with crimped-loop and zip-tied to wire bundle for safety.
+^Testing|Tested by powering the aircraft, and resetting 7.5 circuit breaker. Jumpered Thermal Switch sensor to ground to activate relay (required because temperature was not below 40 degrees, and the aircraft is not in the air).|
-For the aircraft to be flyable, awaiting the acquisition of a replacement line heater, we disconnected the lead going to the line heater, and also clipped that wire near the point it connected to the heater, and removed the line heater. Tied back the lead with crimped-loop and zip tied to wire bundle.
+^Result|System seems stable, aft drain mast is obviously heated, measured by feeling it from outside.|
-Tested by powering the aircraft, resetting 7.5 circuit breaker. Jumpered Thermal Switch sensor to ground to activate relay (required because temperature was not below 40 degrees, and the aircraft is not in the air). System seems stable, aft drain mast is obviously heated, measured by feeling it from outside.
+^Remaining Steps|We will need to acquire a replacement Forward Drain Mast, and Fill Solenoid Ribbon Heater, and install them.|
 ===== Steps to the Solution, Narrative =====
@@ Line 64: / Line 71: @@
 ==== Captain's Circuit Break Blown ====
-The Pilots discovered that the circuit breaker **Galley Supply 1** was thrown. After some thought, it was concluded that this was caused by some troubleshooting on a previous session. This breaker apparently is upstream of the Galley Heaters, including the Drain Mast and Line Heaters.
+The Pilots discovered that the circuit breaker **Galley Supply 1** was thrown. Photo shows the breaker in the thrown position, although it is hard to see. After some thought, it was concluded that this was caused by some troubleshooting on a previous session. This breaker apparently is upstream of the Galley Heaters, including the Drain Mast and Line Heaters.
 {{:projects:challenger604:captaincircuitbreakers.jpg?direct&400|}}
@@ Line 72: / Line 79: @@
 [9/25/2019] We looked at additional locations, including in the tunnel, and in the closet. (We looked in the closet because there was another J103 connector in the tunnel, with wiring traced to the cabin closet. This wiring was evidently part of the emergency lighting system.) While my brother
-was looking in the closet, I was bored and looked in some of the drawers. Noticed when looking
+was continuing our search by looking in the closet, I rechecked some of the galley drawer backs. Noticed when looking behind the ice box, there is a panel with screws in the corners. We removed this, and the
-in the ice box that there was a panel with screws in the corners. We removed this, and the
+relay panel was inside. Although we had examined nearly every other drawer in the lower galley area (below the counter), we hadn't noticed this before this day. No documentation available to us explained the location of the important panel. The only explanation was "Lower Galley."
-relay panel was inside. Although we had examined nearly every other drawer in the lower galley area (below the counter), we hadn't noticed this before day.
 **Relay Panel Location**
@@ Line 116: / Line 122: @@
 watts
-Pin C (originally thought was one line heater, but schematic shows various line heaters)
+Pin C (originally thought was just one line heater, but schematic shows various line heaters). These values indicate the short, the subject of this narrative.
 ohms
 .2 amps

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