Stats for Multi vs Singles- Engine Failure rate

[Everskyward]

Yet what about that avweb report that accident rates and serious accident rates were the same for high performance singles and twins?

Those weren't all engine failures, though.

 

[Bob Noel]

Those weren't all engine failures, though.

Right. Engine failures were a subset of the accident causes.

 

[bobmrg]

I understand that a good twin can maintain altitude down low. But don't forget that the overall serious accident rate is pretty much the same for high-performance singles and twins. So whatever extra safety is provided by the 2nd engine is lost due to other failure modes.

Any certificated twin is controllable on one engine. I can think of only one, the Champion Lancer, that cannot maintain altitude on one. Based on weight and and stall speed, Part 23 requires a positive climb rate on one engine at a density altitude of 5000 feet.

Bob Gardner

 

[Bob Noel]

Any certificated twin is controllable on one engine. I can think of only one, the Champion Lancer, that cannot maintain altitude on one. Based on weight and and stall speed, Part 23 requires a positive climb rate on one engine at a density altitude of 5000 feet.

Bob Gardner

Idle curiousity: The 150hp Apache can maintain altitude on one engine?

 

[Mtns2Skies]

Idle curiousity: The 150hp Apache can maintain altitude on one engine?

Barely

 

[Jaybird180]

Right. Engine failures were a subset of the accident causes.

Did I forget to bracket the thread to engine failures? Isn't this idea of redundancy the reason for the controversy in the first place?

 

[Ted]

Did I forget to bracket the thread to engine failures? Isn't this idea of redundancy the reason for the controversy in the first place?

I think the real question is how you determine redundancy. You won't achieve the same performance on one engine that you do on two, but that's something that makes the cover of "Duh" magazine.

But the idea that most twin proponents (including me) point out is that in a lot of cases, it does give you more options should an engine fail. The Chieftain is probably the most worrisome of the twins I fly in this respect, the 310 Colemill the least.

 

[Fearless Tower]

Idle curiousity: The 150hp Apache can maintain altitude on one engine?

Kind of depends on the altitude you are trying to maintain.

 

[Fearless Tower]

Did I forget to bracket the thread to engine failures? Isn't this idea of redundancy the reason for the controversy in the first place?

You did specify that it was a matter of engine failures, however, as several of us pointed out, the best you can do is speculate - you will not find the data you seek because successful landings after engine failure in both singles and twins don't always get reported.

Even when there is an accident following an engine failure, it may not get reported correctly - I recently listened to an ATC tape of a Bonanza that made an emergency landing at an airport here in SoCal after losing its engine. However, when I looked up the accident report, all it stated was that the airplane was damaged when it made a hard landing - no mention of the engine failure or emergency that precipitated the hard landing.

 

[Everskyward]

Part 23 requires a positive climb rate on one engine at a density altitude of 5000 feet.

Pretty sure this is not true.

23.67

(2) For each airplane that meets the requirements prescribed in §23.562(d), or that has a VSOof 61 knots or less, the steady gradient of climb or descent at a pressure altitude of 5,000 feet must be determined with the—

(i) Critical engine inoperative and its propeller in the minimum drag position;

(ii) Remaining engine(s) at not more than maximum continuous power;

(iii) Landing gear retracted;

(iv) Wing flaps retracted; and

(v) Climb speed not less than 1.2VS1.

I read that as the climb or descent gradient must be measured, not that it must be positive. In addition, it must be measured with the gear and flaps up and the prop feathered.

 

[sba55]

Pretty sure this is not true.

23.67

I read that as the climb or descent gradient must be measured, not that it must be positive. In addition, it must be measured with the gear and flaps up and the prop feathered.

FAR 23 also doesn't apply to most older twins. I might be wrong on that.

Twins under 6-something thousand lbs gw also don't need to demonstrate a positive SE takeoff rate. The rules change a lot for twins above that weight.

 

[Bob Noel]

Did I forget to bracket the thread to engine failures? Isn't this idea of redundancy the reason for the controversy in the first place?

well, when that avweb article was posted, the thread (or at least part of it) drifted into the overall safety of twins compared to other aircraft.

 

[denverpilot]

Kind of depends on the altitude you are trying to maintain.

FTW! +1

 

[flyingcheesehead]

Any certificated twin is controllable on one engine. I can think of only one, the Champion Lancer, that cannot maintain altitude on one. Based on weight and and stall speed, Part 23 requires a positive climb rate on one engine at a density altitude of 5000 feet.

Pretty sure this is not true.

23.67

I read that as the climb or descent gradient must be measured, not that it must be positive. In addition, it must be measured with the gear and flaps up and the prop feathered.

I was gonna say, I don't think the Seminole can stay at 5000 feet on one. Book single-engine service ceiling (50 fpm ROC) is only 3800 feet. Single-engine absolute ceiling can't be much higher than that.

Idle curiousity: The 150hp Apache can maintain altitude on one engine?

As someone else pointed out... It depends what altitude!

I did my Comm-AMEL in a 150hp Apache, and it actually would climb on one. We were near max gross weight, too. However, it was November and DA was probably <1,000 at altitude.