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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39
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7answers
8k views

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 ...
34
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4answers
17k views

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") ...
31
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7answers
32k views

Why do airplanes use AC electric power?

Primary electric power on larger airplanes is provided as AC. What aspects of aircraft make AC a better choice than DC?
29
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8answers
7k views

Why do we still need ammeters?

I just received my private pilot's certificate 2 weeks ago, yay! Earlier today, a fellow at work who has 700ish hours walked in and asked my office-mate-electrical-engineer "why do we still need ...
29
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2answers
7k views

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 ...
24
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2answers
14k views

How are fly-by-wire airliners controlled in case of complete electrical failure?

In this comment, it is postulated that even fly-by-wire aircraft (Airbus) are demonstrated to fly without any electrical systems. All Airbus aircraft are demonstrated controllable with complete ...
23
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2answers
12k views

Where is the generator in a large turbofan of a commercial airliner?

So, where do you put the electrical generator? If it's gonna be coaxial, the only place is the rear (it will be burnt) or the front (it will get in the way of intake). If it's gonna be coupled to a ...
23
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3answers
6k views

Does electrical usage contribute to fuel consumption?

I know that while in-flight the electricity is produced by the engines. What happens if every possible system requiring electricity is in the on state? This ...
23
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2answers
3k views

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 ...
22
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3answers
7k views

What happens when disengaging the electricity generators on a B747?

This answer says: If let's say, you [...] disengage the electricity generator of every engine (which cannot be re-engaged without mechanical maintenance), [...]. What exactly happens in the ...
21
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3answers
53k views

Why is Hydrazine used to power the F-16's EPU?

Why does the military use hydrazine to power the F-16's Emergency Power Unit (EPU)? What is so unique about Hydrazine fuel that it's needed to power the EPU? Why not use a less volatile and less ...
20
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2answers
5k views

How stable is the "customer" power on a commercial aircraft?

This question on Travel.SE got me thinking... Just how stable is the power that's available via the outlets in the passenger cabin on a modern, commercial aircraft? My assumption in my answer that it'...
20
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3answers
12k views

How does the A350/380 operate on Variable Frequency AC generators?

To keep a constant frequency of 400 Hz, most aircraft have a CSD (Constant Speed Drive) associated to the AC generator. On most types (e.g. A320, A330, B737, B747, B777) an Integrated Drive Generator (...
19
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6answers
6k views

Why are Li-ion batteries not being used in aircraft but are widely used in electric vehicle industry?

This might seem a very naïve question. Maybe the comparison of electric vehicle to aircraft is hugely inappropriate. But I couldn't find a clear answer in web search. Lithium-ion batteries have a high ...
19
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3answers
4k views

Can a completely drained battery be recharged via ground power on an airliner like the B737?

When accidentally leaving the battery switch or something powered by the hot battery bus on over night, an aircraft's battery could completely discharge. Normal startup, where the battery is switched ...
16
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9answers
19k views

Can rotorcraft pick up a dangerous electric charge?

So, I was re-watching The Hunt For Red October, (in light of current Russian shenanigans with Sweden), and there was a scene in which a crew-member on the ground was electrocuted by making contact (...
16
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3answers
10k views

How much electrical power does one generator produce on a large turbofan?

From my related question, now I want to know just how much power does the generator produce? In other words, what is the max rating of the generator? It looks so small and that surprised me, but since ...
16
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2answers
3k views

Are there commercial airplanes that are still flyable without any electricity? [duplicate]

I have seen the first episode of Revolution yesterday and there are all kinds of airplanes just falling from the sky because of complete loss of electricity. I know most if not all modern planes use ...
16
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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°, ...
16
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1answer
2k 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 ...
14
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3answers
4k views

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?
14
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1answer
4k views

Where are the circuit breakers on the 787?

(787 left, 777 right) Normally found aft of the overhead panel, where are they on the Boeing 787?
14
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1answer
562 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 ...
13
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3answers
3k views

What's the point of separating the Alternator and Battery switches?

What's the point of having a different button for the battery? Why does the alternator turn on simultaneously with the battery? I need an easy and short explanation, if possible.
13
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2answers
29k views

Why do aircraft use 400 Hz AC instead of the 50 or 60 Hz of wall outlets? [duplicate]

Large aircraft electrical systems usually use 400 Hz alternating current (AC), while common household electrical outlets deliver AC at 50 or 60 Hz. Why the difference?
13
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3answers
4k views

What is the shed bus in the Phenom 100?

I recently came across a part of the electrical system of aircraft named SHED BUS. I am specifically asking for the Embraer Phenom 100. Source (Page 122), Added ...
12
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6answers
10k views

Do commercial aircraft have electrical outlets?

As we see trains nowadays with sockets for you to plug your laptop into, as well as Wi-Fi on-board both trains and planes, I'm wondering why you don't see electrical outlets on planes? Do any ...
12
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1answer
1k views

What is the low resistance design path in an aircraft to withstand a lightning strike?

I know in a building we have lightning rods that conduct a lightning strike into the earth, but for an aircarft there is no ground to 'ground' so I assume the lightning enters and passes through the ...
11
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3answers
3k views

What lights does the Cessna 172 light rheostat control?

I am part of a team developing a Cessna 172 P model for FlightGear, an open source free flight simulator. We are now programming how the panel and radio lightning rheostat should work, but we found a ...
10
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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)?
10
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1answer
4k views

What is the process to disconnect ground electric power before pushback?

While commercial airliner are parked at the gate, they have electrical power connected to the aircraft (if available at the airport). This needs to be disconnected before pushback - what is the ...
10
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2answers
1k views

What are the advantages of using DC electric power over AC, as e.g. done in the EMB 135/145?

In this question I can see the advantages of using AC electric power over DC in large aircraft. However, Embraer decided to produce a "DC aircraft": the ERJ 135/145. What are the advantages ...
10
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2answers
2k views

How common are 400Hz supplies in aircraft?

I understand that 400Hz, 26Vrms power is found in a lot of aviation equipment. But how common is it? Is it in every plane and every instrument or is it restricted to certain sectors, like military, ...
9
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3answers
4k views

Is there any electrical component on an aircraft which can never be turned off by a pilot?

Am I correct to assume that every electrical system on an aircraft can be manually switched OFF/ON by the Pilot OR is there indeed any system, on which the Pilot does not have the ability to switch ...
9
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7answers
7k views

Will the landing gear work mechanically in case of total power loss?

In case of a total power failure in all the aircraft systems like engine failure and APU failure, would it be possible to use mechanical means (manually) to open the landing gear bay door and deploy ...
9
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1answer
6k views

What is the difference between frequency wild AC system and other AC systems?

What is the difference between a standard AC system and an "AC wild" system? How does the latter work?
9
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2answers
3k views

How do virtual circuit breakers work?

In AW189, B787 and few other aircraft/helicopter, the physical breaker has been replaced by virtual breaker, which can be controlled by the MFD (Multi-Function Display). I tried to google the answer, ...
9
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1answer
1k 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 ...
8
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5answers
6k views

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 ...
8
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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 ...
8
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2answers
4k views

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).
8
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1answer
3k views

What could cause the APU on a Boeing 777 to fail and also trip the GPU?

I am a cargo aircraft loader at Heathrow and while we were offloading cargo, pallets and baggage containers from a Pakistan Airlines B777, the aircraft's Auxiliary Power Unit (APU) failed. It made ...
8
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1answer
812 views

Were cabin lights really consuming that much power back in 2006?

Even though it is nine years since then, I can still clearly recall my return flight from London Luton to Katowice (Poland), that I took on July 31, 2006 evening. There were a huge, strong storm front ...
8
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1answer
965 views

What causes a "BATT DISCHARGE" CAS message on the Phenom 100E?

In the Phenom100 POH the descriptions for the "BATT DISCHARGE" CAS message is "During a normal system operation, at least one battery is discharging." I'm a bit confused as to what exactly does ...
7
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2answers
3k views

Why do airliners still have a switch for the non-smoking sign?

I've wondered why airliners have a switch in the cockpit to turn off the non-smoking sign. Why isn't it illuminated all the time, or a better question: Why is it still there, now that everybody should ...
7
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1answer
4k views

What does BUS mean in the startup procedure?

I noticed the term BUS in the startup procedure of a 737. What do BUS on, off and transfer mean and what is their significance?
7
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1answer
424 views

What is the time before an alarm is given after a fire sensor perceives a fire?

I've got a very specific question: When a fire sensor perceives a fire, does it wait 20 or 60 seconds before giving the alarm?
7
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3answers
1k views

What are the pros/cons of ram air turbines?

Commercial aircraft are equipped with ram air turbines that can be deploy to provide power in case all other sources of power are lost. Ram air turbines have the benefit of providing power as long as ...
6
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3answers
4k views

How does an aircraft recharge its batteries?

I assume aircraft have batteries that power up all electronic devices on board. But how are these batteries recharged? When the aircraft is on the ground, it can be connected and recharged in the ...
6
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1answer
297 views

Can I do an alternator check at idle in a C152?

I have one question about alternator check in Cessna 152. During engine run-up we should check whether alternator is working or not, so we switch it off and then the warning light should illuminate. ...