Single turboprop commercial IFR

[4Greens]

There is a proposal to allow single engine commercial ops in IFR for the Uk. Any views on this would be welcomed.

[Aluminium shuffler]

Once again, safety takes a back seat to cost and convenience...

[Global Aviator]

Old news the Aussies been doing it for years as with others.

ASETPA.

Still thing if prefer 2 donks!

[MrMachfivepointfive]

The PC12 and the Caravan are amazing aircraft. So, why not? Two engines across an ocean? OMG! If progress had not prevailed, we would today cross the pond in 10-engined turboprops like the SaRo princess.

[windypops]

2000 hours on multi engine aircraft with PT6 engines and I've seen 2 major failures.

[MrMachfivepointfive]

2000 hours on multi engine aircraft with PT6 engines and I've seen 2 major failures.

I will not get on an airplane with you. You are unlucky. The mean time between failures for the PT-6 is 346,000 hours.

[oceancrosser]

I will not get on an airplane with you. You are unlucky. The mean time between failures for the PT-6 is 346,000 hours.

:D hilarious!

But back to the topic. This is bound to happen in certain areas. There has been very little development in the 8-12 pax sector in the last 35-40 years.
Lots of Navajos, Chieftains and C402s were flying domestic sectors when I was learning to fly in the late seventies. Some of these are still around, even in the USA Cape Air is operating close to 80 C402s.
There has been development in single engine turboprops, but less so in smaller twins in this size category and none in piston engined planes AFAIK.
Perhaps this will come to something http://www.tecnam.com/Traveller/P-2012-Traveller.aspx

[FlyingOfficerKite]

This idea was proposed by Dave Willmott and others at Emerald Airways in the '90s.

Didn't get anywhere with the authorities - irrespective of whether the routes were over land or sea.

The proposal was for a 'spoke and hub' arrangement with single-engine turboprops feeding into larger airports where (in those days) HS748s, F27s and Electras would carry loads further.

This would have made commercial sense, it was suggested, with lower operating costs on the shorter, lighter routes.

Apparently this arrangement is common in the US (?)

[Agaricus bisporus]

With just 1000hrs in a C208, all of it over inhospitable bush I'd have no hesitation in supporting this.

There must be a huge untapped market out there for this sort of thing as long as it isn't strangled by the bureaucrats, not to mention an excellent training ground for newbies and a big stir-up of the employment scene.

It us done safely and routinely all over the world, why not here?

But how many pilots? One or two? I expect a second "pilot" who is in reality no more than an employed passenger would knock the bottom line out of the balance sheet and cripple the whole thing. Else second pilots will be paid nowt which isn't progress. Even so that's a waste of 80Kg of payload.

FO Kite, that's the system FedEx have been using for decades. They operate hundreds of Caravans - see their website.

[rigpiggy]

Just over 10k PT6 time, 2 precautionary shutdowns "prop seal, and nicked oil line, 1 that ate itself. Not in favour

[Airbanda]

It us done safely and routinely all over the world, why not here?

IMHO issue in UK is population density and therefore greater risk that when (and it is when not if) there's a failure that impact will be on populated area.

[172_driver]

It's already being done in Scandinavia for cargo, in quite inhospitable environment. Winter, icing, open sea: Nordflyg Air Logistics | Nordflyg Air Logistics (http://logistics.nordflyg.se)

[jiggi]

Done in Finland also: Home - Hendell Aviation Oy (http://www.hendellaviation.fi/en/home-.html#.VDAEyRaGdW0)

It doesn't have any relevance but AFAIK the scale of the operation is quite small.

[FlyingOfficerKite]

FO Kite, that's the system FedEx have been using for decades. They operate hundreds of Caravans - see their website.

Yes, you've jogged my memory - it was precisely that FedEx model that Emerald were hoping to emulate in the UK.

[lomapaseo]

Once again, safety takes a back seat to cost and convenience...

Isn't that the same when you drive to work?

Safety is relative and in this case as in all aviation it's defined and codified in the regulations for one to read before getting out of your car and onto a plane.

The plane wasn't designed unsafe, it simply is now allowed to take willing passengers.

[20driver]

Surprised no one has mentioned this incident. This guy landed his PC-12 on main drag in South Bend.
PC-12 Makes Remarkable Street Landing In Indiana | Aero-News Network (http://www.aero-news.net/index.cfm?do=main.textpost&id=7cf257ed-2453-41a3-9e1c-7b25974cf6ae)

Hope that link works but if not it was a PC-12 , 22RG, in December 2004

[Heliarctic]

This is how it was in 2007.
Single- and twin-turbine accident rates similar | Aviation International News (http://www.ainonline.com/aviation-news/2007-10-09/single-and-twin-turbine-accident-rates-similar)

And PC-12 vs Kingair and other TP aircraft
Single Engine Turboprop Safety | Western Aircraft (http://www.westair.com/aircraft-sales/single-engine-turboprop-safety/)

And single engine TP safety 2012
http://www.flightglobal.com/airspace/media/safetyreports/emptys/103503/single-engine-turboprop-business-utility.pdf

Personally wouldn't be concerned with it.

[Capot]

Small turbo-props seem quite prone to shut-downs, don't they? Maybe it's because of the operating environment most work in.

My phone has rung twice in the small hours after double-engine failures in twin-engine aircraft I was responsible for, engaged in civil air transport operations.

By the way, "mean time between failures for the PT-6 is 346,000 hours" does not mean that each engine can be expected, on average, to operate for 346,000 hours without an unplanned shutdown (aka failure).

That statistic is perfectly consistent with various pilots' experiences described here of multiple failures in relatively small numbers of hours, presumably with all the PT6 variants.

I'm sure that there's someone here who can explain the interpretation of MTBF data, and its relationship to real operations, better than I can. All I know is that it makes me very wary about being in a twin over large expanses of water/inhospitable land. (See above re phone calls).

[ahramin]

The mean time between failures for the PT-6 is 346,000 hours.
Great statistic, but it excludes failures of external components like fuel pumps and oil lines, both of which you need for the engine to keep running. It's great for setting standards and comparing engines, but a discussion of single engine IFR should include total engine failures for any cause, which isn't even tracked.

[peekay4]

A discussion of single engine IFR should include total engine failures for any cause, which isn't even tracked.
The relevant metric is called IFSD (engine in-flight shutdown) which is tracked and reported by law. E.g., for ETOPS operations the FAA requires that the 12-month rolling IFSD rate for the aircraft type/fleet worldwide must be less than limits set in 14 CFR 21.4 (ETOPS Reporting Requirements).

An engine event is considered an IFSD if it ceases to operate or is shutdown in flight for any unplanned reason (internal failure, icing, bird ingestion, etc.).

The mean time between IFSDs for PT6 is 125,000 hours. This is calculated for the population. E.g., if you have a fleet with 100 PT6s operating, then expect an IFSD over the entire population average 1,250 hr.

The 346,000 hours is actually not the MTBF of PT6s, but the mean time between engine failure accidents for PT6 equipped Cessna 208 Caravans.

This does not mean a particular Caravan will make it 346,000 hrs before an engine accident. In fact, only a minority (1/e = 1/2.71) = 37% of Caravans can be expected to reach this amount of hours without an engine accident.

[currawong]

I will not enter the debate as to single engine air transport ops.

However, I would comment that something is going very, very wrong somewhere for the failures reported here to be occurring with such frequency.

[The Ancient Geek]

One of the problems here is IFR. A small aircraft such as the Caravan or PC-12 can usually find somewhere for an emergency landing in VMC, even a city street. This is fine until IMC conditions leave you with little chance to find a safe spot.

Another issue is the typical operator of such small operations, like it or not their aircraft are not going to be maintained quite as scrupulously as someone like Fedex with a large fleet.

Is there really a market in the UK ?. IFR operations implies routes between properly equiped airports. Is there really a market for scheduled 12 seat operations between major airports with ILS etc or are we talking about ad hoc charters and other GA calling IFR when the weather gets wormy en route.

[peekay4]

The irony is that the experiences in Canada and US have shown that collectively single-engine turbopros are -- statistically speaking -- as safe or safer than twin turboprops.

See for example the annual reports on turboprop safety from Breiling & Associates. Every year single-engine turboprops have accident rates (and fatal accident rates) comparable to, or better than, turboprop twins.

In Europe, single-engine commercial IFR is already a reality in a number of countries (France, Spain, Sweden, Finland, Norway, etc.) operating under EASA exemptions.

What's being proposed is to harmonize the rules EU-wide. I believe the new rules will come into effect in 2016.

[Capot]

To continue the statistical line, 51,000 or so PT6 engines have been built in 50 years. Let's assume (complete guess) that 20% have been scrapped, and that 70% are on an aircraft, with 10% in overhaul, or in the spare engines cupboard.

So that's 35,700 on an aircraft. Many of those are corporate, private even, and fly very few hours. Others will be busier. My absolute guess is that the average hours per day is 2.

If that's anywhere near right, those engines will fly 75,000 hours a day, so using Peekay4's data we can expect an IFSD on a PT6 every 1.67 days, somewhere in the world.

Bit of a guess, really, but you get the point. How many would occur in the UK depends on the UK's share of those PT6 hours.

I would have thought that the only really useful IFSD data would be variant-specific; apart from the basic concept there doesn't seem to be much in common between the early ones and the latest, most powerful versions.

experiences in Canada and US have shown that collectively single-engine turbopros are -- statistically speaking -- as safe or safer than twin turbopropsSomeone did comment that the causal factor there is that pilots are a damn sight more careful about loads, conditions, etc etc with only the one donk in front; the inference being that accidents in twins mostly occur as a result of loss of thrust on one engine. Let's not forget the BN2A Islander, in a similar context. And, of course, that you are twice as likely to experience that loss if there are two engines.

I know, I know, but it's Sunday afternoon and statistical howlers are permitted.

[4Greens]

Somewhat puzzled as to why this topic was removed from Rumours and News to Questions. It is an important safety issue and needs the widest possible circualtion. Most people I know ( including me) have never used 'Questions '. I had to do a search to find the topic again.

[Amadis of Gaul]

But you found it, and that's what matters.

[gordon field]

EASA NPA 2014-18 Commercial air transportation aeroplane operations at night or in IMC using single engine turboprop aeroplane is the document you should read. Comments are due by 17 Oct 2014. It's on their website.

The relevant safety cases are fully explored with very detailed information on engine reliability.

What is an anomaly is that they propose a risk period of 15 minutes when the aircraft is not within gliding distance of a suitable landing site and that this 15 minutes can only be used ONCE per flight. To my knowledge risk periods such as originally proposed for ETOPS have been on a continuous basis, not just on one occasion.

The engine reliability data does not take into account the cycles/hours and quality of overhaul on any of the engines that have failed.

All of the aircraft have, unlike MET aircraft, an emergency power lever.

What the NPA does not list are the hundreds of SET aircraft that have been regularly flying in the EU for many years at night and in IMC, naturally privately of course. How many of these have fallen out of the sky due to failure of the powerplant or systems?

Having listed and explored all of the reported accidents to SET aircraft around the world the statistics show that it is still the lack of pilot's adherence to mandatory and recommended procedures that results in the majority of accidents and fatalities.

I hope that you will read and digest the information given and comment as you see fit. Don't shoot from the hip otherwise your comments will not be taken seriously.

[Caboclo]

I think there are two different mindsets in this debate. One is Once again, safety takes a back seat to cost and convenience...

The other is "Get rid of this gov't Health and Safety crap and let us decide for ourselves what we're willing to risk."

I'm not a shrink, but I suspect that both positions are based deep in the psyche, and neither will be easily swayed by mere facts.