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====== Heated Drain Mast ======

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.|


We are now trying to obtain a replacement Drain Mast heater.

  * Info: http://www.airframer.com/direct_detail.html?company=113946
  * Submitted a quick internet form to get a price to: https://aerobasegroup.com  [7/10/2019]
  * Sent another RFQ to https://crsjetspares.com/ [7/10/2019 1:45 p.m.]
  * Sent another https://www.aerospaceunlimited.com/rfq/thankyou?name=Dan%20Wheeler&Cname=604%20Challenger&Ctype=Airlines/Charter%20Operator&email=dan@quizkid.net&phn=206-387-7127&Part=115677-114&need=Immediate%20Buy&Qty=1&IsnewsLetter=False&type=rfq [7/10/2019 5:33 p.m.]

Note that while this schematic page is excellent, what is absent from the drawing is that Pin B1 on the relay is actually connected to Pin c (lower case, with bar), which connects to "L" in a hex shape and then to multiple line heaters via two terminal blocks.

{{:projects:challenger604:fr_395.jpg?direct&600|}}

===== Circuit Breaker =====

The relevant circuit breaker (probably not defective): 7274-11-7 1/2 Klixon, 7.5 amp. The schematic specifies that the expected draw is .96 amps. There are two Drain Masts. The forward was open, and the rearward was about 64 ohms (about 100 ohms expected). This circuit breaker supplies 115V at 400 Hz.

**Galley Circuit Breakers**

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 =====

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).|

^Result|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 =====

We invited David Hill to assist with the repair. In preparation of this, prepared the following notes, which describes some of the steps taken.

-------------------------------

[typed 9/25/2019] Disconnected Forward Drain mast connector at J11. Heater (white to White/Blue) measures open. 
(Unpowered, relay off) Measured resistance in connector, which measures resistance of Aft Drain Mast, measures 64 ohms.

Pilots noted that Drain/Line Heater circuit break popped during flight. Likely because "Gnd In Air" activated relay K16.

Powered system. Disconnected connector Thermal Switch connector J31. Jumpered across the two pins. 
Jumpered J31 connector pulls diode cathode to ground. Even with Forward Drain mast connector disconnected, 
Drain/Line Heater circuit breaker pops immediately.

Disconnected AFT Drain Mast Heater at J21. Repeated same test as above, with Powered system, and 
Jumpered connector J31, Drain/Line Heater circuit break pops immediately.

Searched and cannot find J103, or Relay K16. Assuming it is in "Cabin Control Accessory Unit", schematic 
Drawing 34-138W021 says it is in "Lower Galley" because relay K17 is in the Cabin Control Accessory Unit, 
and because J103 (which has about 40 pins) is shown as connected to K16, and also to the Cabin Control Accessory Unit.

Circuit breaker only pops when relay K16 is activated, an important fact.

[9/25/2019 conclusion] Suspect J103 has damage around pins a, b, or c. Or Relay K16 has unused pin B1 grounded or is otherwise damaged. //Turned out this conclusion was close. Pin B1 was grounded, but via additional Line Heater wiring. See schematic below.//

David came today to help with the Challenger 604.

==== Captain's Circuit Break Blown ====

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|}}


==== Found Relay K16 ====

[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 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 
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 Location**

{{:projects:challenger604:lowergalleyrelaypanel.jpg?direct&600|Lower Galley Relay Panel, behind Ice Box}}

**Relay K16 Closeup**

{{:projects:challenger604:relayk16inpanel.jpg?direct&300|Relay K16}}

Looked at relay K16. [[https://www.lintechcomponents.com/product/013960626/M8353610024M/81349|Some relay info]] It functions correctly. Took home, measured fine - checking for shorts. Noticing
that even when powering with 25 volts, less than the 28 rated, it is getting quite warm, so going
to run it for a while to see if internal shorts develop. Draws about 76 mA.

{{:projects:challenger604:relayk16closeup.jpg?direct&400|}}


But what seemed to be the root cause is that on pin B1 of the relay, which connects through J103 pin c,
there was a 16 ohm load. This was unexpected.

{{:projects:challenger604:canonplusbackofrelayk16panel.jpg?direct&400|Canon Plug at rear of relay panel}}

[9/26/2019] But when we looked at the schematics, discovered that this
is connected to a line heater. The schematic for the Drain Mast (above) doesn't show anything connected to pin c, or relay B1. 

This probably accounts for the circuit breaker blowing.

---------------------------

**Schematic** showing wiring for Line Heaters. The heater which was shorted to the bolt is called "FILL SOLENOID" wire 1WTR017H18. The terminal block called "1WTR TB2 LAV VANITY" is actually located in the panel at right of Cargo Hold. Wire with a "L" in hex shape goes to the K16 Relay, Pin B1, via wire ''c''. Because this was the solution, we did not need to find TB1 (Terminal Block 1). A wild guess is that it is located somewhere behind/below the galley sink.

{{:projects:challenger604:midcoastwatersystemschematic_r.jpg?direct&400|}}

==== Line Heater ====

The rear drain mast was a 64 ohm drain

Drain Mast:
   64 ohms
   1.79 amps
   207 watts
   
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.
   16 ohms
   7.2 amps
   827 watts
   
What we didn't know at the time we measured the resistance is that Pin C is actually connected to about 8 line heaters shown in the schematic. The "FILL SOLENOID" heater was shorted to ground.

   
[9/26/2019] Brother opened right-hand wall of cargo hold, exposing some of the plumbing for the cabin water supply. 

{{:projects:challenger604:rightcargoholdplumbing.jpg?direct&600|}}

A terminal block is present. Measured resistance of each of the 5 wires to ground, found one, H1B, that had low resistance, approximately 30 ohms. On close examination, noticed that the wire went to wiring that was wrapped into foam insulation. When opening it, found charred ribbon heater end. Measured resistance, and noticed that movement cause resistance to fluctuate. Looked under heater end, saw that it touched sharp nut point, which was also charred.

==== Ribbon Heater ====

{{:projects:challenger604:ribbonheaterlabelreverse.jpg?direct&300|}}

{{:projects:challenger604:ribbonheaterlabel.jpg?direct&300|}}

According to other references, the unreadable part number was probably 3043-110-6-621.

{{:projects:challenger604:ebayribboncloseup.jpg?direct&600|}}

Ebay possible match: https://www.ebay.com/itm/NOS-Gulfstream-P-N-3043-110-6-21-Heater-Ribbon/263828284040?hash=item3d6d642288:g:qZgAAOSwLB9bU49w:sc:USPSFirstClass!98055!US!-1&autorefresh=true
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