Some of the gauges, e.g. fuel temperature and APU EGT, made by myself, based on information I found on the internet. Basically the same design as Opencockpits uses. The gauges with two needles I bought from OC. For the time being the gauges are ok, but certainly I will replace them sometime in the future.

Engine Start Switches
The Engine Starter Unit (solenoid with some mechanics) I got from simparts.de. The unit is quite easy to install and needs a short 12V pulse in order to reset the engine start switch from the GRD position back to the OFF position. This happens with reaching approximately 56% N2. In order to prevent damage of the switching circuit a free-wheeling diode is connected in antiparallel to the solenoid. The switching pulse of ~ 100ms is produced by a SIOC script which is monitoring N2 during the engine start sequence.

Engine start switches with solenoids. At the upper right corner you can see
one of the relay circuits (blue box).

simparts: http://www.simparts.de//, search for 'Engine Starter Unit 737'

Battery Switch
The battery switch of the overhead acts as the main power switch of  the flight deck. As long as the switch is in the 'OFF' position only the OC interface cards, USB hubs, and some other interfaces are supplied with operating voltage. The cockpit is in the so called 'Cold and Dark' condition. With the battery switch 'ON' the 'switched'  power supplies getting activated, the display units (e.g. PFD. ND, EICAS) and other components are getting 230V. Furthermore the 'ON' status is read by the pmSystems software and the flight deck becomes alive. For more information see 'Power Supply'.

System Software
Most of the overhead functionality is controlled by pmSystems. The interfacing between pmSystems and the hardware is performed by a comprehensive SIOC script, which includes some extensions for additional functions and add-on integration.

The LED's for the OH panels are located inside the cover of the OH, build up by ~5m of LED strips. Only for within small area were the interfaces are mounted the LED's were placed on a support structures below the interface cards. Next step will be to add a PWM (pulse width modulation) dimming circuit for the LED brightness control.

The Overhead at night

The FWD Overhead backlit is integrated in the top cover of the OH

Ceiling Bracket
The overhead is mounted to the ceiling by the means of 4 threaded rods, with a diameter of 12mm each. This was a quick and economic solution, but will become an issue with the installation of the AFT OH. For the time being I can live with this constraint, but definitely I will think about another solution in the near future.

Overhead ceiling support.


Last Change: October 2011