# Why are there so many steps to starting an engine on a plane? Why not a turn-key start? **URL:** \ **Category:** Factual Questions\ **Created:** [July 25, 2020, 9:15am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306 "2020-07-25T09:15:19Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [July 29, 2020, 4:58pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/61 "2020-07-29T16:58:07Z")
> [@Machine\_Elf](#): > > Is this really necessary in helicopters? The rotors spin up awfully slowly; seems like they wouldn’t catch anybody by surprise. Yes. The tail rotor spins up very quickly and can be hard to see. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [July 29, 2020, 5:13pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/62 "2020-07-29T17:13:19Z")
Also, you don’t need to duck to avoid the main rotor in the helicopters I’ve flown. The tail rotor, you can walk right into. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 29, 2020, 7:38pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/63 "2020-07-29T19:38:23Z")
But only once. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [July 29, 2020, 9:10pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/64 "2020-07-29T21:10:17Z")
(about waking into a tail rotor) Now I’ve got that scene from _ER_ where Dr. Romano wandered into a tail rotor, as well as an old _Monty Python_ bit where it is asked “Did you say knives?” “Yes, rotating knives.” ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 29, 2020, 9:45pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/65 "2020-07-29T21:45:29Z")
A few years ago we had a light plane pilot here who was struck by the prop of his plane when the engine farted once while he was working on it. Fortunately it didn’t stay running. He got a pretty good head wound but survived. His wife posted on his behalf for awhile. I’m not recalling his username or whether he ever came back. I searched a bunch for the thread but couldn’t find it. I don’t think it was just a few posts in the ginormous general aviation thread. Nothing funny about these things. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [July 30, 2020, 1:58am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/66 "2020-07-30T01:58:28Z")
> [@LSLGuy](#): > > A few years ago we had a light plane pilot here who was struck by the prop of his plane when the engine farted once while he was working on it. Fortunately it didn’t stay running. There are also entrenched horror stories of people hand-propping an engine. Then, when the prop is spinning and nearly invisible, they forget it’s there and step forward to remove the chock from the wheel. Oops. Another mistake you do at most once. I had occasion once to install a chock under a wheel after shut-down while the pilot was still in the cockpit. I made sure to call out “Is the switch off?” first and get an affirmative answer first. And I STILL made sure to stay away from the prop path. Be careful around airplanes! ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [July 30, 2020, 8:37am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/67 "2020-07-30T08:37:53Z")
Bottom-line: the go-roundy bits are NOT your friend! ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [August 3, 2020, 4:16am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/68 "2020-08-03T04:16:46Z")
> [@Broomstick](#): > > Bottom-line: the go-roundy bits are NOT your friend! Well, when you’re on the ground outside of the plane, they’re not. Once you take off and head into the wild blue yonder, though, they _are_ your friend and you want them to keep going round. 😉 Because if they stop, it gets awfully quiet up there… ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [August 5, 2020, 6:42pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/69 "2020-08-05T18:42:52Z")
Funny enough, there are examples of aircraft where you GRAB the prop as it starts. The Bristol Britannia (actually a CC-106 Yukon) had a habit of the prop spinning backwards if the wind was right so the ground crew would hold the prop until the turbo spooled up and it walked out of your hand. One of my co-workers had to do it and said it was probably the most unnerving feeling in the world to know the engine was running and the prop was in your hand! ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [August 6, 2020, 2:09am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/70 "2020-08-06T02:09:50Z")
You can hold the prop on a free-turbine turboprop as it is driven by the exhaust gasses and doesn’t have a direct connection to the rest of the spinning parts of the engine (don’t try it if the prop is _already_ spinning of course!) The ATR72 can use an engine for auxiliary power on the ground and has a prop brake to stop the prop from spinning in this mode. > **[ATR 72](https://en.wikipedia.org/wiki/ATR_72)** > > The ATR 72 is a twin-engine turboprop, short-haul regional airliner developed and produced in France and Italy by aircraft manufacturer ATR (French: Avions de transport régional or Italian: Aerei da Trasporto Regionale), a joint venture formed by French aerospace company Aérospatiale (now part of Airbus) and Italian aviation conglomerate Aeritalia (now Leonardo S.p.A.). The number "72" in its name is derived from the aircraft's typical standard seating capacity of 72 passengers. > During the 198... > Most operators of the ATR 72 equip their aircraft with a propeller brake (referred to as “Hotel Mode”) that stops the propeller on the No. 2 (right) engine, allowing the turbine to continue running and provide both airflow and electrical power to the aircraft while on the ground. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [August 6, 2020, 1:08pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/71 "2020-08-06T13:08:10Z")
> [@Richard\_Pearse](#): > > You can hold the prop on a free-turbine turboprop as it is driven by the exhaust gasses and doesn’t have a direct connection to the rest of the spinning parts of the engine (don’t try it if the prop is _already_ spinning of course!) There must be some point during the main turbine spool-up at which the torque delivered to the prop (via the prop’s power extraction turbine) exceeds what can be held back by human hands. I’m guessing that happens before the main turbine arrives at its normal idle RPM? ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [August 6, 2020, 6:46pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/72 "2020-08-06T18:46:51Z")
Yes presumably. A mechanical brake can hold it at idle though. ---
**Author:** ![Just\_Asking\_Questions](https://avatars.discourse-cdn.com/v4/letter/j/ba9def/32.png) [@Just\_Asking\_Questions](https://boards.straightdope.com/u/Just_Asking_Questions)\ **Post date:** [August 6, 2020, 8:15pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/73 "2020-08-06T20:15:30Z")
> [@Tride](#): > > I’ve been lucky enough to fly quite a bit in a Bell 205 helicopter (skiing). I’ve been told by several of the pilots that if you don’t do the starting procedure EXACTLY right you blow up the turbine. That’s finicky and kind of crazy. The owner of the ski company is a licensed helicopter pilot and he can fly the machine but said he would never attempt to start it! I think they’re exaggerating. They used to let “kids” start them in Viet Nam. Start procedure for a 205: Put throttle to idle Run starter until proper engine speed, release starter let engine speed up to idle Watch for things not going right If you have a failed start, and then attempt again without motoring the fuel out, now there you can have an exciting start that will possibly destroy the motor. ---
**Author:** ![Tride](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tride/32/13907_2.png) [@Tride](https://boards.straightdope.com/u/Tride)\ **Post date:** [August 6, 2020, 11:28pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/74 "2020-08-06T23:28:49Z")
Interesting. They were pretty adamant. This is a 205 that was rebuilt from a totalled airframe (the certification plate was still valid). You would think that would make it more modern than a real Vietnam era 205… ---
**Author:** ![3AxisCtrl](https://avatars.discourse-cdn.com/v4/letter/3/ecd19e/32.png) [@3AxisCtrl](https://boards.straightdope.com/u/3AxisCtrl)\ **Post date:** [August 7, 2020, 12:46am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/75 "2020-08-07T00:46:59Z")
To the OP’s question “Why not a turn-key start?” A trend in newer aircraft is toward what’s known as a [FADEC](https://en.wikipedia.org/wiki/FADEC): full authority digital engine control. As the name suggests, this means a computer handles most everything, very likely including much or all of the start sequence. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [August 7, 2020, 12:48am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/76 "2020-08-07T00:48:22Z")
> [@Richard\_Pearse](#): > > Most operators of the ATR 72 equip their aircraft with a propeller brake (referred to as “Hotel Mode”) that stops the propeller on the No. 2 (right) engine, allowing the turbine to continue running and provide both airflow and electrical power to the aircraft while on the ground. Why only the right engine? I understand that the left engine would be shut off entirely, but wouldn’t the prop still be able to spin especially if the wind picks up? Wouldn’t want the passengers hit by a windmilling propeller. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [August 7, 2020, 1:05am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/77 "2020-08-07T01:05:23Z")
If there’s a concern about the prop windmilling then it can be tied with a bit of cord, much cheaper than a brake designed to prevent the prop turning on a running engine. I’ve never flown an ATR so I don’t know if the left prop is typically tied on a turn-around or not. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [August 7, 2020, 1:09am UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/78 "2020-08-07T01:09:14Z")
It looks like there’s a tie on the prop in this photo. [![](https://www.nzherald.co.nz/resizer/G2MvGTK7lgusIXDRDm747tPcwLg=/620x349/smart/filters:quality(70)/arc-anglerfish-syd-prod-nzme.s3.amazonaws.com/public/VPOV62E3RZGGBN7SKOWSNXDWN4.jpg) ](https://www.nzherald.co.nz/resizer/G2MvGTK7lgusIXDRDm747tPcwLg=/620x349/smart/filters:quality(70)/arc-anglerfish-syd-prod-nzme.s3.amazonaws.com/public/VPOV62E3RZGGBN7SKOWSNXDWN4.jpg) ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [August 7, 2020, 12:22pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/79 "2020-08-07T12:22:00Z")
> [@Tride](#): > > Interesting. They were pretty adamant. This is a 205 that was rebuilt from a totalled airframe (the certification plate was still valid). You would think that would make it more modern than a real Vietnam era 205… Starting even a primitive turbine isn’t difficult. But the steps must be followed accurately. If you brain fart or your finger slips off a switch at the wrong moment you can spend a lot of money. Like maybe more than that helo can earn in profit in a year. So the owner’s point wasn’t that it was difficult. It was that he didn’t want to play “you bet your business” unnecessarily when he had experts who practiced the same maneuver every day. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [August 7, 2020, 1:54pm UTC](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306/80 "2020-08-07T13:54:58Z")
Back when I was flying helicopters, one of the owners of the FBO was talking about a 206. He said, ‘They’re great aircraft… if you can get them started.’ What made the remark funny was that earlier that day I was interrupted while going through the checklist. Neither I nor my instructor could get the R22 started. As the instructor was wracking his brain to figure out why the engine wouldn’t start, I noticed that the thing I missed when I was interrupted. The mixture control was still at idle cut-off. My instructor said, ‘Let’s not tell anybody.’ So when the other owner/instructor made his comment at dinner, we just looked at each other sheepishly. 😛 [Previous page](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306.md?page=3) [Next page](https://boards.straightdope.com/t/why-are-there-so-many-steps-to-starting-an-engine-on-a-plane-why-not-a-turn-key-start/916306.md?page=5)