Welcome Guest. Sign in or Signup

7 Answers

Why is there both an Alternator and Generator on Bell 412 EP?

Asked by: 4838 views Aircraft Systems

I want to know that why there is a need of both Generator and Alternator in Bell 412 EP. Both are for charging purpose than why Both are installed in this Machine ?

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

7 Answers

  1. CFI Academy on Sep 20, 2011

    I am not familiar with Bell 412 EP, but I can simply assume that alternator charges the battery, and battery supplies power to some/most electrical equipment. 
    And because there might be a need for even more electrical energy, which the battery can sustain, they might have installed a generator, instead of adding more batteries and more alternators to support the system.
    I may be completely wrong here, but it was worth the try. 🙂

    0 Votes Thumb up 1 Votes Thumb down 1 Votes

  2. Steve Brack on Sep 22, 2011

    I haven’t found anything that states definitively why it has both, but I’ve noticed that complex turbine aircraft often have some systems that require AC to run & others that run on DC.  Perhaps having an alternator (to generate AC) and a generator (to generate DC) was the way this helicopter’s designers elected to provide both AC & DC power.  This is simply informed supposition on my part, however.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes

  3. Brian on Sep 22, 2011

    Many gas turbine helicopters are configured with a generator and alternator. Many others are configured with just a generator, such as an older Bell 412 that one of our pilots used to fly. The main reason for a generator is more power per unit weight. In other words, for an alternator to give the same amount of power it would weigh more. Further, generators provide AC power, where as alternators require an inverter; adding even more weight and complexity. Much of the heli equipment/instruments, even more so in medivac choppers, runs off of AC power.
    Long story short, helicopters consume  massive amounts of energy and a generator attached to the turbine shaft can supply it with far less weight. Or so I was told by our sikorsky crowd when I asked them today. I really have no clue if this is right, but it sounded good 🙂

    0 Votes Thumb up 0 Votes Thumb down 0 Votes

  4. Matthew Waugh on Oct 03, 2011

    Is it a starter/generator – some (most?) small turbines use a starter/generator to perform both the start and electricity generation. If it is then you can’t have a starter/alternator, so that explains the generator.
    So if you need extra power you either add a bigger generator, or for redundancy another generator (but I think generators are heavy as opposed to alternators) so they might have just chosen to throw an alternator on it.
    But what do I know?

    0 Votes Thumb up 0 Votes Thumb down 0 Votes

  5. Kris Kortokrax on Oct 18, 2011

    There is not an alternator installed on the 412.
    Each engine has a starter/generator.  This is one piece of equipment which serves as a starter motor when electrical power is supplied throught the start circuit.  After starting, the unit serves as a generator.  Each engine has a starter/generator.  These supply DC power and charge the batteries.
    In addition, the helicopter will have two inverters.  The inverter supplies AC power.  Typically, one inverter is selected and the other serves as a backup.

    +2 Votes Thumb up 3 Votes Thumb down 1 Votes

  6. William on Jul 21, 2012

    A snag recently enoucnterd on a Bell 412EP Griffon Army Helicopter: One power section(PS), would at 71% N2, throttle locked, then go to roll up the other power section, and the previous power section would drop off to 61% This happened on both sides, didn’t matter which PS was rolled first the same thing happened. Any takes?

    0 Votes Thumb up 0 Votes Thumb down 0 Votes

  7. William on Jul 21, 2012

    oops I should proof read the last^^^

    0 Votes Thumb up 0 Votes Thumb down 0 Votes

The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.