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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6
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1answer
717 views

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

The 737 Classic has two different possible styles of engine-driven generators, distinguished by the generator's drive mechanism: the constant-speed drive (CSD) and the variable-speed constant-...
20
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3answers
11k 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 (...
6
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1answer
230 views

Do I need a ferry permit for an alternator repair ferry flight within a mode C veil?

My Cessna 172 SP's alternator died while stationed at a class D airport, less than 10 miles from my home field (another class D). Both airports are within the mode C veil of a nearby B airport. ...
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 ...
6
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1answer
467 views

What is the battery voltage for a Supermarine Spitfire?

I am used to modern aircraft being 28V systems. I found an article saying that a trolley AC plug in battery used to start WWII aircraft was 12V. I'm trying to confirm or disprove this.
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 ...
16
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9answers
18k 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 (...
3
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4answers
2k views

What component of an aircraft generates its electric power?

What component of an aircraft generates the electric power to start the aircraft's engine? For a Rotax 912 engine, I think the magneto generates the electricity, but I'm not sure; I also think about ...
6
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3answers
2k 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 ...
4
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1answer
1k 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?
-1
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3answers
189 views

What amount of electricity could we get from the Seebeck effect on a kerosene turbofan?

Edit: I rewrote my post. To downvoters, can you comment on your reasons? As a kind reminder: Downvote questions that don't show any research effort or don't contain enough information to be clear and ...
4
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2answers
259 views

Why is the alternator connected only to one electrical bus in the C152?

I am a noob in electrics so pardon my ignorance. What I see from an electrical system of C152 (pasted below): there are two busses, connected to each other, but alternator is fed only to the first bus....
5
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1answer
728 views

Why battery voltage is lower than system/alternator voltage

I’m a noob in electricity so pardon for my ignorance. Why the battery voltage is always lower than whole system and alternator voltage (considering light aircraft electrical system). E.g. In Cessna ...
6
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1answer
284 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. ...
2
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2answers
500 views

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 ...
1
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1answer
460 views

Why are these steps performed on the A330 emergency electrical checklist?

For an Airbus A330 in emergency electrical configuration with both generators and APU FAIL (both engines working), why does the checklist ask you to select RAT MAN ON before slat extension and then ...
0
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1answer
187 views

Where can I find maintenance manuals for the A380?

My friend recently acquired an external green light from an A380. They are the only details i have from him. I tried hunting the internet for maintenance manuals, technical details, schematics, ...
5
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2answers
2k views

Why is the battery turned off for checking the voltage on the A320?

Preliminary cockpit preparation section requires BAT check for 25.5V with BAT off (The beginning step). Since BAT indicator always show respective voltage, why they must be switched off?
6
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2answers
955 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 ...
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 ...
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 ...
2
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2answers
145 views

Can I safely plug something that draws 6 amps into the cigar lighter (power port) in my Piper Archer lll?

Can I safely plug something that draws 6 amps into the cigar lighter (power port) in my Piper Archer lll ?
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1answer
177 views

Will reducing the electricity power in an aircraft save fuel?

I was wondering if I reduce the power consumed by the aircraft, would the generator produce less power and if that would save some fuel.
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6answers
310 views

Would a piston or turbine engine be best suited for a small UAV flying 8000miles?

I am trying to devise a concept that would airdrop medical supplies around remote regions of Africa: vaccines, medicine, blood... etc. I image the payload would be anywhere between 1-2 ton. I think a ...
4
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1answer
456 views

What is the most commonly occurring fault with this type of electrically driven gyro?

I have an examination tomorrow about advanced avionics systems (EASA module 13) and we are required to troubleshoot a fault with the compass system. What is the most commonly occurring fault with a ...
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2answers
1k views

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 ...
2
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0answers
102 views

How many smoke detectors does the A340 cargo deck have, and how are they wired?

I am a student of Aerospace Engineering, currently I am one year away from completing my degree. For my Electric Routing class I was asked to recreate in Catia the fire system in the cargo bay of an ...
2
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0answers
121 views

What is the cost of electricity generated in the E175-E1?

I'm comparing two types of cabin illumination, and I'm having a difficult time to estimate the cost that will be saved by utilizing lights with a lower power consumption. What are the costs of ...
5
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1answer
324 views

Why can APU supply both bleed air and electrical power up to 10.000 feet but bleed air alone up to 17000?

I am reading my company's FCOM and I saw there the following information. APU Bleed + Electrical Load: Max Alt 10000 ft. APU Bleed: Max Alt 17000 ft. APU Electrical Load: Max Alt 41000 ft. If APU ...
21
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3answers
52k 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 ...
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)?
2
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1answer
291 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 ...
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).
2
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3answers
630 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)....
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 ...
9
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7answers
6k 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 ...
1
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4answers
527 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 ...
3
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2answers
277 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 ...
5
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1answer
216 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 ...
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 ...
1
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1answer
763 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 ...
34
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4answers
16k 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") ...
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 ...
1
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2answers
505 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. ...
5
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1answer
617 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 (...
3
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0answers
101 views

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 ...
14
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1answer
546 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 ...
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?
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 ...
6
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1answer
880 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 ...