Questions tagged [electrical-system]

The parts of an aircraft that produce electrical power (such as generators/alternators, batteries, and ram air turbines) and distribute it to the aircraft's systems.

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3answers
3k views

What happens with the avionics if in midair there is loss of power or fuel flow interrupted? [duplicate]

What happens if in midair there is loss of power, how will the avionics perform in such a situation (cockpit display, flight plan)?
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1answer
237 views

Why are the 737's variable-speed generator drives so unreliable?

The 737 has three different possible styles of engine-driven generators, distinguished by the generator's drive mechanism: the constant-speed drive (CSD), variable-speed constant-frequency drive (VSCF)...
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1answer
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Are the A320's A and B electrical buses both energized all of the time during flight?

I'm a novice reading a quick study guide. For electric power, I notice that the A320 has two buses: A and B. Are they both energized all of the time during flight? If not, is there a way to switch ...
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How is the 747-100's ground-handling bus protected against being energised by the engine-driven generators in the event of a bus-to-bus short?

The NTSB report on the non-crash of UA811 includes a detailed description of the operation of the 747-100's lower-lobe cargo door and the associated electrical circuitry, as well as an explanation for ...
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1answer
170 views

If an A320 loses an engine why does the landing category go to CAT3 single?

Following an A320 engine failure, why does the the landing category go to CAT3 single even if the APU has been started and is powering the AC bus that was lost by the failed engine?
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2answers
136 views

Why do the DC-9’s three-phase electrical systems use separate, unconnected breakers for each phase?

Aircraft electrical systems use two types of electricity: Direct current (DC),1 which always travels in the same direction (can be supplied directly from the aircraft’s battery, if necessary, but ...
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4answers
398 views

Is it possible to reload Electric Aircraft in mid-air from a tanker aircraft?

Can this be done military style refueling but with an electric wire boom supplying current from tanker aircraft to electric aircraft mid air in flight? Electricity from the tanker craft can be ...
5
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1answer
146 views

Where is the control loop of the actuator closed?

When electro-hydraulic servo-actuators are used for the actuation of control surfaces in aircraft, linear variable differential transformers (LVDTs) are used for position or velocity feedback. There ...
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1answer
208 views

How much power does the APU generate in a Boeing 737-300?

I have just watched Mayday episode 11, season 11, "Nowhere to Land" about TACA Flight 110 incident and I was more than surprised to learn that: APU must be turned on, APU needs about 5-10 minutes to ...
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4answers
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What does “28 volts DC” mean, really?

The common battery voltage on aircraft is commonly referred to as "28 volts". What does that really mean in terms of a lead-acid battery? In many uses, such as cars ("12V"), trucks ("24V") ...
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7answers
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What prevents a commercial jet from electronically “resetting” the way a computer sometimes does?

I've had a fear of flying for the past several years and one of the ways this irrational phobia manifests is concern over the airplane power-cycling in mid-air: engines cutting out, control equipment ...
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2answers
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How does the battery master switch activate the battery contactor in Cessna 152?

I have trouble understanding how the battery master switch activates the battery contactor in this schematic from the Cessna 152 manual. This is the model from 1979 or later with an Alternator Control ...
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2answers
268 views

Why does the low voltage warning light not illuminate when the alt switch is on, but the engine is off?

As part of the pre-flight inspection, one of the checks is to verify that the low voltage light is illuminated when switching just the battery on. This makes sense; there's a low voltage and the ...
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2answers
148 views

Where to find general A320 E&E Compartment Information?

I'm student in electrical engineering and write my thesis on some topic of the e&e compartment. The main focus is on the computers of the A320 flightcraft, actually called E&E Compartment. ...
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0answers
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Why was the Tu-104 so prone to navball-disabling electrical power failures?

Of the (rather numerous) accidents involving the Tu-104, several were either caused or aggravated by major electrical failures, which disabled the aircraft's navballs, which caused the pilots to ...
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1answer
417 views

What's the plug used on airliners for ground power?

What's the plug pair called? What's the ISO/whatever standard involved? What do they look like close-up? Is it pretty standard today worldwide? Is the plug identical for the hugest airliners as for ...
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3answers
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What powers an aircraft prior to the APU being switched on?

I know that APUs are power plants for non-propulsion related purposes and that they are turned on before takeoff. What powers an airplane prior to the APU being turned on?
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1answer
335 views

Why does the B737NG need electrical power for aircraft towing?

I have read the AMM for towing and one of the mentioned steps is to supply electrical power. Is it because you need power to turn on the hydraulics in order to pressurize your brakes? For B737NG
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1answer
74 views

Where can I find electrical pinout of C152 microphone jack and DC bias?

Would anyone have the pinout and/or specs of the C152 passenger/pilot microphone jack? I'd also like to know what DC bias voltage, if any, the plane provides to the microphone. Here's what I have so ...
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1answer
192 views

What is the source of emergency power for a 727?

I've found a couple of sources that state the 727's APU cannot be started while flying, as it draws air from the wheel well. It drew air from inside the wheel well, so it was only for use on the ...
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1answer
234 views

Why is the generator turned back off for starting the second engine on a King Air?

The engine start procedure for the Beechcraft King Air B200 says (emphasis mine): Right Ignition and Engine Start Switch – ON [R FUEL PRESS] annunciator – OFF Right Condition Lever – LOW IDLE (...
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What is the working principle of VFG [duplicate]

How does the VFG make various frequencies? And while it makes the other value of frequency, how the generator apply consistent 400Hz to the other component?
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1answer
3k views

What happens to Cessna electric flaps that are moving when power is lost?

On final in a C182T you move the flap control arm from 20 to FULL, and when halfway there, the breaker pops (or BUS1 fails, a wire falls off, etc.) Does the flap stay where it is, slide back to 20°, ...
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1answer
642 views

How can the F-16 remain stable when there is a loss of hydraulic power?

Edit for justification: This question is different from If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky? for the following reasons: The ...
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5answers
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Has there ever been an airliner design involving reducing generator load by installing solar panels? [duplicate]

Has there ever been a trial/project/design, in which solar panels were incorporated in the design of a commerical airliner (e.g. on the wings), with the aim to reduce fuel consumption by lowering the ...
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2answers
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Is aluminum electrical wire used on aircraft?

Aluminum electrical wire got a bit of a bad reputation in household wiring due to reacting badly with terminals not properly rated for aluminum. Properly handled, it works fine, but it's so ...
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1answer
652 views

What are possible causes for the flaps not deploying on a Cessna 172?

I would like to seek some expert opinion on why my flaps failed to deploy when I took it to Flaps 20. I was turning from Downwind to Base when I took flaps 20 and noticed that my speed was creeping ...
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0answers
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Are there required standards for gate power cable maintenance?

I am looking for reference(s) addressing gate power cable maintenance, for both 28V DC and 400Hz. Do the FAA or any manufacturers have standards for measuring the connector pins to determine wear?
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0answers
143 views

Ground Power KVA when on stand

How much power from a GPU would a jet, say a Boeing 737, require when boarding passengers or just sat idle on the air bridge? I’m guessing the Aircraft would only consume the full 90kVA ground power ...
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3answers
439 views

Does the 2020 ADS-B -Out requirement apply to aircraft with only a wind-driven generator (electrical system)?

Since my J3 Cub was was not originally certificated with an engine-driven electrical system it's clear the 2020 ADS-B-Out mandate (U.S.) does not apply (except where specifically noted in FAR part 91)....
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2answers
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What is the “off-side engine generator” on an A320?

For the A320 family, is the "off-side engine generator" the same as the "emergency generator driven by the RAT"? I can't find the location of the "off-side engine generator" on the A320.
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3answers
686 views

Why does load shedding still occur in jetliners (e.g., 787) when there is so much power available?

I had a few questions about how electrical generator works on an aircraft, the 787 to be specific although I know it is similar for all aircraft. So the 787 engines have 2 VFSG each which are rated ...
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1answer
138 views

What is a Ground Power Dispatch Switch?

I've been going over the new Master Minimum Equipment List (MMEL) for Textron Aviation Model 500 Series Citations and on page 36 a Ground Power Dispatch Switch is mentioned but I can't find any ...
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2answers
1k views

What is the standard power supply and voltage supply on modern airliners?

I'm looking at reducing the weight footprint of some of the computer systems on a commercial liner. A big consumer of weight seems to be in power supplies and conversion. Being a computer guy, I don't ...
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1answer
642 views

How does the automatic battery cut off logic prevent complete battery discharge on ground in the A320?

I was reading in the electrical systems of the a320 FCOM and in one of the notes it stated that the batteries have an automatic cutoff logic which prevents them from getting completely discharged when ...
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1answer
1k views

What is an “all-electric APU”?

Understand that the APS5000 used in the B787 is the first all-electric APU for large commercial aircraft. Source: http://www.pwc.ca/en/engines/auxiliary-power-units Sorry if this sounds too ...
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1answer
149 views

Is it possible to 'retrofit' electric flight control actuators to replace existing hydraulic actuators on aircraft?

Read a bit about the potential cost savings of replacing existing hydraulic aileron actuators on large commercial aircraft such as the A350/380 with electrohydraulic/electromechanical actuators. ...
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1answer
255 views

What does Phase 3A mean for avionics?

I've learned about Phase 1, Phase 2, and Phase 3 electrical systems. But recently I've faced an issue about replacement of Phase 3 Common Display System (CDS) Display Units (DUs) with new Phase 3A CDS ...
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0answers
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Where can I find power and heat specifications for EFIS and IFE systems?

I am working on an MSc. thesis project about the electrification of aircraft. Since the rule of thumb is to design the generators for the worst case scenario, I would like to include as much ...
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0answers
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Is there a standard place to find detailed wiring circuit and component information for different aircraft?

Today I was looking into the systems that are affected by the STDBY ATTD (#1 and #2) circuit breakers in a SR22 and I accidentally stumbled upon something that I find very interesting and I've been ...
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2answers
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What happens when all electrical systems in a helicopter fail?

I was thinking of asking this question at Worldbuilding, because it is for a book I am writing, but I hope this site will fit better. You can migrate this question if you find Worldbuilding more ...
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1answer
147 views

What type of batteries are used in airline planes? [closed]

In Embraer 145 and Boeing 777 I mean material, recharge cycle, nominal current and voltages. From the comments I don't understand the difference if the plane is turboprop or turbofan.
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2answers
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What is the typical voltage used on jet airliners?

I have seen several parts that use 28 Volts DC, is this a standard for jet airliners (e.g., Airbuses and Boeings).
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1answer
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Why is there an altitude limit if we have an IDG failure on the A320?

In my company’s MEL there is an altitude restriction if we have an IDG failure of 33500 feet why is that?
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1answer
401 views

What are the “Start & Acc” and “Pitch stab” circuit breakers for on the Piper Dakota?

I am learning to fly a piper dakota and I found two circuit breakers for which I can't find an explanation: Start & Acc circuit breaker. I understand that 'Start' is for the starter. What does '...
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2answers
443 views

How are batteries cooled in passenger aircraft?

What sort of systems are used to cool batteries in the air? Liquid cooled? Air cooled? I am interested in lithium chemistry batteries in the form of either pouch cells or 18650 batteries inside of ...
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2answers
2k views

How do electric anti-icing systems work?

How do they work for GA propeller planes? More specifically, how is it implemented on the leading edge of the wing and propeller blades? I'm more interested in the mechanics of electric heating, not ...
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1answer
532 views

What's field excitation in an electrical system?

"A field relay in the GCU (generator control unit) allows or prevents field excitation within the generator. When open, the field relay deprives the associated power relay of its ground, which causes ...
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2answers
1k views

Am I correct about what AC/DC BAT BUS does?

The purpose of the AC/DC BAT BUS is to distribute either A/C electrical power and D/C electrical to the things in the aircraft that need them. For example, I think he whole ECAM system and displays ...
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4answers
2k views

Can quadrotors be used for commercial passenger flights? [duplicate]

Recently, I have been conducting research on more efficient means for vertical lift transportation. One direction I was thrown in was the use of a quadrotor system with vector thrust and artificial ...