1VE the misunderstood abomination
Lets understand the 1VE problem, since many here are not Doinker people.
The operators of the Do328-300 can’t solve the 1VE problem but are left with an end result equation. Common fault isolation can be achieved using the DC Breakout box. The Breakout Box will not address problems upstream of the Generator Control Unit nor will it tell you anything if the system is not hard failed. A Breakout box is simply a series of clearly identified jumpers where voltage readings can be taken without opening the system.
The heart of the "todays" problem in the DC Generation and Control System is not the 1VE per say but the Hall Effect Sensor.
http://www.micronas.com/products/overview/sensors/index.php
The Heart Corporation originally manufactured the 1VE, if you look at some of the Dornier wiring manuals, you will sometimes see it referred to as the Heart Panel or 1VE. The 1VE gets its name from the first engineered component within the VE (electrical) system and 2VE, A/C Generation and Control was next, etc.
The Heart Corporation was offered engineering plans from Dornier and told to build the unit. Heart told them they were smoking crack and the units would not hold up under real-time operational loads. The Germans are very bullheaded you see and insisted this was a perfect design, sound familiar? Now begins the sticky part.
I visited with Barfield in Miami and made them demonstrate to me proper tear down of the 1VE and what did I find, over temped Hall Effect Sensors (HECS) on APU side. HECS are $2800 each. Thermal tape is now being applied directly to HECS to monitor heat ranges.
The HECS can only take about 65C (149 Degrees) of temperature variance and become unstable or smoke check beyond that range. Sometimes when the units drop below 65C they will become functional again. Each time they are over temped they become more erratic and failure prone. INTERMITTENT the scurge of every mechanic or electricain.
The problem with the 1VE is the design plain and simple. The HECS are being over temped from improper design. You see this German engineered beauty supports; DC Generator System, Battery System, Emergency DC Power System, APU/DC Starter/Generator System and External Power. If you’re Turbo Prop add engine starting to that equation.
The real problem can be traced to circuit share. The Right/APU systems share the same path logic but the left side is left independent. Had the Germans sectioned the box into three independent control schemes, instead of two, there would be no problem. Since the RH/APU shares the same circuits the heat becomes transferred to the what? That's right the HECS. Ever wonder why you have 10 to 1 in squawks between the LH DC systems as opposed to the R/H/APU DC System. Ever wonder why aircraft with no APU do not experience the same 1VE troubles.
I know because Great Plains operated the only Part 121 mixed fleet, Props and Jets, in the USA, ever. Talk about a glution for punishment huh? The entire time we operated the 328-100 (Prop) we changed only one 1VE and it went into parts saver and the GCU was found at fault.
There is apparently an answer on the horizon, with the advent of a new HECS sensor to be released sometime in summer. The new "MOD D" Sensor will be completely redesigned with thermal dissipation in mind. The new sensors will include components more suited to thermal protection and provide working architecture past the 65C barrier.
So the next time you see residual Amperage on your electrical system page and your pulling up that center floorboard remember the average repair of a 1VE is $20K.
Thanks Dornier for making a brilliant aircraft, **CENSORED****CENSORED****CENSORED****CENSORED**ing it up with inferior support, dragging your feat for so many years with poorly designed systems and then blaming the customers. The following statement is why this company failed.
Love,
TechRep