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One of the more unique aspects of the Boeing B-17, in comparison to her contemporaries, is that the majority of the aircraft’s systems were electric.  While it was common for heavy bombers, such as the Avro Lancaster and Consolidated B-24, to predominantly rely on hydraulics, the B-17 only had two hydraulic systems: the brakes and the cowl flaps.  Outside of that, every other system was electric.

The B-17 was equipped with a 24V DC electrical system, powered by four engine-driven generators and three batteries.  Secondary sources of power included two 115V AC inverters located under the pilot seats, a 3V AC transformer, and a portable HRU-28 generator located by the waist entrance.  The bomber’s electrics were divided into fifteen separate circuits, spare blueprints of which were kept in a folder on the back of the copilot’s seat.

Master Wiring Diagram – Blueprint 15-11699
Master Radio Wiring Diagram – Blueprint 15-10987

(A & M) Instrument Circuit – Blueprint 15-11918
(B) Bomb Control Circuit – Blueprint 9-6470
(CR) Command Radio Circuit – Blueprint 14-2350
(D) Deicer & Pump Circuit – Blueprint 14-3710
(E, IB, IL) Lighting Circuit – Blueprint 9-6284
(FL) Autopilot Circuit – Blueprint 9-6498
(I) Ignition Circuit – Blueprint 9-5613
(IFF) Identify Friend & Foe – Blueprint 9-6464
(IN) Intercom Circuit – Blueprint 14-3306
(LR) Liaison Radio Circuit – Blueprint 9-5817
(P) DC Power Circuit – Blueprint 9-5778
(R) Retraction Motor Circuit – Blueprint 9-6463
(RC & MB) Radio Compass and Marker Beacon Circuit – Blueprint 9-5620
(S & PF) Starter & Prop Feather Circuit – Blueprint 9-5770
(W) Warning Signal Circuit – Blueprint 15-10645

It is the goal of Hangar Thirteen to install these circuits as accurately as possible.  Period wiring was covered in lacquered fabric, with 3/32 labels (wrapped in Scotch tape) spread at 10 ft intervals to identify each line.  Acquiring this much lacquered-fabric wire should prove to be an adventure.

But before then, we must start with the various junction and fuse boxes located throughout the aircraft’s fuselage.  This page is intended to serve as a reference for Hangar Thirteen volunteers in that regard.

Blueprint 55-7332: Electrics Installation

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Radio Compass Relay Panel

Radio Compass Relay: 46-8832-B

Components:

BK-22 Relay COMPLETED
2x Fuses – 10 Amp (3AG)
4x Fuse Clips – 3AG

Assemblies:

Fuse Chart (Blueprint 1-27640-2)
Shield Assembly (Blueprint 43-12785-C)

Instruction Plate (Blueprint 1-24967) COMPLETED

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Autopilot Junction Box

Autopilot Junction Box: Blueprint 9-6617

Assemblies:

Bus Connector (Blueprint 1-30461), (-1)
Chart (Blueprint 6-15235)
Shield Assembly (Blueprint 9-6612)
Tab Indicator (Blueprint 1-30460-1), (-2), (-3), (-4), (-5), (-6), (-7)
Terminal Block (Blueprint 3-21928)

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Voltage Regulator Panel

Voltage Regulator Panel: Blueprint 15-7985-E

Components:

Type B-4 Relay (94-32324)

Assemblies:

Bus Connector (Blueprint 25-862-2)
Cover Assembly (Blueprint 3-14221)
Shield Assembly (Blueprint 14-2870-B)

Channel (Blueprint 9-5040-7), (-8)
Fitting Assembly (Blueprint 9-5040-4)

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AC Fuse Panel

AC Fuse Panel: Blueprint 6-10493-C

Components:

2x Fuses – 5 Amp (5AG)
2x Fuses – 10 Amp (5AG)
4x Fuse Clips – 5AG

Assemblies:

Box Assembly (Blueprint 6-10492-B)
Bus Connector (Blueprint 1-26449)
Fuse Chart (Blueprint 1-29928)
Panel Assembly (Blueprint 4-908-5)

Bus Connectors (Blueprint 21-7401-1), (-2)

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Cockpit Fuse Panel – Left Side

Cockpit Fuse Panel: Blueprint 55-7538-E

Components:

B-1B (ON/ON) Switch (AN3014/AN3022-3B)
26x Fuses – 5 Amp (5AG)
2x Fuses –10 Amp (5AG)
38x Fuses – 15 Amp (5AG)
8x Fuses – 20 Amp (5AG)
4x Fuses – 30 Amp (5AG)
2x Fuse – 40 Amp (5AG)
6x Fuses – 60 Amp (5AG)
2x Fuses – 30 Amp (1AG)
2x Fuses – 100 Amp (1AG)
172x Fuse Clips – 5AG
24 Volt Relay SC-C-324-D

Assemblies:

Fuse Chart (Blueprint 3-20633) COMPLETED
Fuse Shield (Blueprint 54-2079-C)

Decal (Blueprint 3-16111-9) DRAFTED

Panel Assembly (Blueprint 75-7635-609)

Bus Connector (Blueprint 1-26270)
Bus Connectors (Blueprint 6-10678), (-2), (-3)
43x Bus Connectors (Blueprint 21-7401-1)
2x Bus Connectors (Blueprint 41-277-11)

Panel Insulator (Blueprint 1-21942)

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Cockpit Fuse Panel – Right Side

Cockpit Fuse Panel: Blueprint 6-12625-D

Components:

10x Fuses – 15 Amp (5AG)
4x Fuses – 30 Amp (5AG)
20x Fuse Clips – 5AG
Relay – Four Pole, Double Throw 2028 (Leach Relay)

Assemblies:

Fuse Chart (Blueprint 1-29168) DRAFTED
Panel Assembly (Blueprint 3-19627-4)

Bus Connector (Blueprint 1-27913)
10x Bus Connectors (Blueprint 21-7401-2)

Panel Insulator (Blueprint 3-19632)
Relay Assembly (Blueprint 3-16974)

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Wing Junction Boxes

Wing Junction Boxes: Blueprint 14-2072-E and -F

Components:

2x CA-275X Capacitors

Assemblies:

Bus Connectors (Blueprint 21-7401-6)
Decals (Blueprint 9-4641-4), (-5)
Insulator (1-25561)
Insulators (Blueprint 3-13696)
Panel Assembly (Blueprint 3-16953)

Bus Connector (Blueprint 1-25543-1)

Panel Assembly (Blueprint 9-3601)
Shield Assembly (Blueprint 6-9325-1), (-4)

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Bombbay Junction Boxes – Ignition

Bombbay Junction Boxes – Ignition: Blueprint 6-7889-A-0 and -A-1

Assemblies:

Box Assemblies (Blueprint 21-8364-A)
Decals (Blueprint 9-4641-13), (-14)
Insulators (Blueprint 21-8627)
Connector Assemblies (Blueprint 21-8891)

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Bombbay Junction Boxes – Generator

Bombbay Junction Boxes – Generator: Blueprint 6-9509-A-0 and -A-1

Assemblies:

Cover Assemblies (Blueprint 41-9981-2)
Decals (Blueprint 6-10790-2), (-7)

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Bomb Rack Junction Box

Bomb Rack Junction Box: Blueprint 15-7967

Assemblies:

Decals (Blueprint 1-24603), (-1)
Decals (Blueprint 9-4641-19), (-36)
Insulators (Blueprint 3-14244)
Panel Assemblies (Blueprint 6-10113)
Shield Assemblies (Blueprint 6-10112), (-1)

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Strike Camera Power Receptacle

Camera Power Receptacle: Blueprint 6-12851

Components:

AN3102-16S-6P Socket Receptacle
2x AN3102-16-11S Socket Receptacles
Type B-5A Switch (Single Throw)
BAC768-B6 Connector Assembly

Assemblies:

Plate (Blueprint 6-12649)

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Liaison Radio Junction Box

Liaison Radio Junction Box: Blueprint 56-7583-A

Components:

Type C-1B Switch

Assemblies:

Bus Connector (Blueprint 21-7401)
Connector Panel Assembly (Blueprint 21-8891-14)
Decal (Blueprint 6-11943-11)
Insulator (Blueprint 21-8627-14)
Retainer (Blueprint 41-158)
Shield Assembly (Blueprint 6-7625)
Stop (Blueprint 41-159)

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Waist Fuse Panel

Waist Fuse Panel: Blueprint 69-3659-D

Components:

2x Fuses – 5 Amp (5AG)
2x Fuses – 10 Amp (5AG)
6x Fuses – 15 Amp (5AG)
6x Fuses – 20 Amp (5AG)
6x Fuses – 60 Amp (5AG)
2x Fuses – 70 Amp (2AG)
22x Fuse Clips – 5AG
2x Fuse Clips – 5AG
P. R. Mallory CA-275X Capacitor (50V)

Assemblies:

Fuse Chart (Blueprint 3-19952-6)
Panel Assembly (Blueprint 7-1646-11)

Bus Connector (Blueprint 1-18567) MISSING BLUEPRINT
Bus Connector (Blueprint 3-14974-2)
10x Bus Connectors (Blueprint 21-7401-2)
Bus Connector (Blueprint 41-277-8)
2x Washer (Blueprint 41-3996-28-17)

Shield Assembly (Blueprint 7-1535)