proper simulated feather power settings

[Jumpindan]

Hello,
I'm looking for a simulated feather power setting (tq and prop %) for a DHC-6 with -27's. We are doing in-plane training and I can't find any manufacturer's recommendations for simulated feather setting in the ATM. I have had conflicting advice on what it should be. Obvoiously, we don't want to do training for single engine operations with the motor actually feathered below patttern altitudes and don't have access to a sim. (Flight safety charges a premium for their way outdated and dying level B sim...) Thanks for the help.

[john_tullamarine]

Until someone jumps in with something specific to Type, a first cut approach is to run two simple trials for the same conditions, including speed. First run motor shut down and the propeller feathered, trim to maintain heading and leave the trim set for the subsequent run. Then restart the engine and set power to maintain heading with the previous trim required with the motor shut down.

[Amadis of Gaul]

What could possibly go wrong?

[Mach E Avelli]

No need to shut a PT-6 down. The prop can be feathered with the gas generator running and the amount of thrust being delivered then is negligible for your purposes.
Run the check as JT suggests at a safe height and speed/flap combination representative of whatever you use to commit to take-off. The operative word here is 'commit'. Aircraft like Twin Otters don't have proper V1 speeds, rather a Take-off Safety Speed which is typically reached at about 50 feet. Certainly the speed that you would typically lift off at would not be a safe speed for simulating an engine failure.
Pilots have trained safely on Twin Otters and the like ever since they were built. But safe check & training pilots are always conservative when simulating engine failures.
Don't accept any heroics pulling back to zero thrust before take off safety speed and at least 50 feet has been reached. Know your book Vmcg before trying any rejected takeoff practice.
Pulling power all the way to flight idle at low speed in the air is a recipe for disaster. Do not do it...ever. The aeroplane has an auto-feather system which is so unlikely to ever fail when needed that it simply does not justify training for that possibility. If your Regulator or anyone else insists on pulling to idle at low speed either throw him off the aeroplane or get off yourself. Or go to a proper simulator.

[john_tullamarine]

Pulling power all the way to flight idle at low speed ..

Wise counsel and relevant to this thread.

Have a read of the report on ANB at the ATSB website (http://www.atsb.gov.au/publications/investigation_reports/2010/aair/ao-2010-019.aspx). A little knowledge sometimes produces dangerous results ..

The video cartoon reconstruction is illuminating, I thought ..

[Jumpindan]

I appreciate the responses. We do not induce V1 cuts for training and only verbally simulate failures below 400ft as per FAA guidance. We don't have an installed auto feather on all our aircraft (some are early model 100's when it was a factory option, not always installed). We train the best we can in the aircraft for manually feathering for V1 cuts by chair flying and talk through/going through the motions. We do use the factory recomendations for V1/V2 speeds and perform balanced field planning. The main thing I am looking for is a good power setting for single engine missed approaches when I want the gas generator spooled for a real world oops when training. The idea of doing approaches/landing to any short field with turboprop/turbine engines pulled to idle and the prop pulled back isn't my idea of a safe or smart idea, especially since we tend to fly into smaller strips with less margin for error. When I have the plane up tomorrow I'll do some experimentation as suggested to find a good compromise. Thanks again for the help.

[Mach E Avelli]

Dan, it sounds like you are taking a responsible and careful approach to this.


If some of your aircraft don't have autofeather, you would be best to train for 'worst case' scenario, in that when the fertilizer hits the fan there may not be time to analyse whether or not the prop has feathered and whether or not to initiate a manual drill. It is usually best to do nothing than to do the wrong thing.


With that in mind, I suggest that you regard V1 as only a V1 for accelerate-stop being guaranteed. Unless your V1 coincides with an unusually high Vr, it is probably not a 'true' V1, in that following a failure at exactly that speed, continued acceleration under control to Vr then further to "V2" is probably not achievable with a prop windmilling and may not even be achievable with it auto-feathered (unless in very skilled hands). By definition, V1 can never be greater than Vr but could be equal to it or considerably less. But the very use of the term V1 implies that having suffered a critical engine failure, continued flight under control in the hands of an 'average' pilot is assured, and this is where if you are not careful, your pilots could be deluded. I am no Twin Otter guru, but from the little I know, when operating from limiting runways, rotation to take-off occurs at some fairly low speeds, i.e. below Take off Safety Speed.
As with many light twins, you should treat the time between "V1" and Take-off Safety Speed as a time when, if an engine fails, you must land as best you can. Better to hit something (hopefully not a brick wall!) at 50 knots wings level than to auger in from 50 feet with no control. On any given flight your exposure to this risk (i.e. unable to continue, unable to stop on the runway) is probably only in the order of 10 seconds or so. Quite an acceptable risk, given the very remote likelihood that the engine will choose those 10 seconds to cark it.


When doing your 'armchair' reviews of procedures, I recommend teaching pilots to leave any attempt to manually feather until above 50 feet and at or above TOSS. If you fly two pilots, PF flies, PNF identifies, PF confirms and PNF feathers......slowly......


The recent chilling video of the ATR 72 in Asia that went in at nearly 90 degrees bank angle should be compulsory viewing.


Anyway, keep up the good work!

[john_tullamarine]

The recent chilling video of the ATR 72 in Asia that went in at nearly 90 degrees bank angle should be compulsory viewing

Indeed. Here (https://www.youtube.com/watch?v=9yBA7qqgnig) or here (https://www.youtube.com/watch?v=msZWc67KYp0).

Near word for word for a similar turboprop prang some years ago for which I was involved in the investigation. Near Vmc is not the place to be playing heroes ...

[Jumpindan]

Mark,
Thanks for the response. When messing around in the plane yesterday I found a good compromise of 7lbs TQ with prop max rpm for a simulated feather setting. This is for a frankin otter. 100 series with 300 series wings and -28 motors. (motors came off a C90 and 337'd for the otter) Because our minimum field lengths don't require MPS takeoffs (our shortest is just under 2000') we almost always do flap 10 takeoffs and rotate mid 70's for our weights. Just wanted to make the clarification that we aren't doing MPS takeoffs, where power to idle and crash within 20 degrees of runway heading is the standard for failures below VMC (often seen with otter pilots doing flap30+ takeoffs and rotating mid 50's). With using a V1 around 73-80kts and a V2/safety speed of 82, the plane will climb just fine in most conditions with a failure if handled correctly and be airborne in 800' of runway. We practice in the sim for initial training but do all recurrent in the plane. If anyone has anything else feel free to PM, I'm always looking for a better way of doing things if it makes safety sense or saves money. (and before someone goes off about an operator putting cost in the equation... I am a firm believer that spending money to train always pays off in the long run. One flat spotted tire is half a months pay to replace, and an accident is company ending..., Hell, being a stickler about airspeeds will save any jump operator $2,000 during a busy weekend. Good VY climb=three minutes off full power climb for same altitude. 50lds/weekend=150minutes of fuel@700lbs/hr saved for the exact same work. Second benefit=your pilots never get too slow and recognize that airspeed matters for staying alive and making money. now off my soapbox!)

[V1... Ooops]

I'm looking for a simulated feather power setting (tq and prop %) for a DHC-6 with -27's. We are doing in-plane training and I can't find any manufacturer's recommendations for simulated feather setting in the AFM.

Read the AFM more carefully, or better still, get yourself an up to date copy of the AFM from the manufacturer.

I wrote the AFM for the DHC-6, and a there is a recommendation for a simulated feather power setting is in the AFM. It is approximately 8 pounds indicated torque at typical single engine cruising speed of 100 to 110 knots. Note that this 8 pounds torque recommendation assumes your torque indicator is properly calibrated.

[V1... Ooops]

...The main thing I am looking for is a good power setting for single engine missed approaches when I want the gas generator spooled for a real world oops when training.

Dan:

It sounds to me like you have the cart in front of the horse when you say that you are "looking for a good power setting for single engine missed approaches".

Set whatever power you need on the single engine approach to maintain the recommended initial approach speed / final approach speed for whatever weight your aircraft happens to be at. The propeller of the functioning engine should be set to 96% Np at the beginning of the approach.

If you have to make a missed approach in single engine configuration, power should be set to 50 torque (with the prop still at 96%) for the missed approach. That is exactly the same power setting that is appropriate for a two engine missed approach.

I have attached an image of the page of the AFM that quite clearly states this.

Michael

http://i979.photobucket.com/albums/ae275/Paneuropean/Single%20Engine%20Landing_zpsecoxyfob.jpg (http://s979.photobucket.com/user/Paneuropean/media/Single%20Engine%20Landing_zpsecoxyfob.jpg.html)

The following page is from Section 10 of the AFM (Safety and Operational Tips), it provides further elaboration of the procedure described in the page above.

http://i979.photobucket.com/albums/ae275/Paneuropean/SE%202_zpsjufz09pv.jpg (http://s979.photobucket.com/user/Paneuropean/media/SE%202_zpsjufz09pv.jpg.html)

[rigpiggy]

On the 1900 used 400#, the KA200 200# on PT6's without flight stops listen for the change in noise as the props fine out

[Car RAMROD]

The Twotter uses PSI not Ft/lbs for the torque gauges so unfortunately those Beech numbers don't give us much help.

[rigpiggy]

basically use 10% of max tq, so i believe the twotter uses 50# so as said earlier 5-8#. ish