Actually it was two accidents for the one Lightning Strike wasn't it?

There was the one where the aircraft got hit by lightning and then the one where the improperly repaired/inspected blade failed on a second aircraft resulting in the loss of all aboard.

The Oil Companies are all for aviation safety....right up to the point it costs them money....at which point they all begin to sharpen their pencils and begin calculating cost/benefit ratio's.

The story I heard was that the blade that was struck by lightning had a manufacturing defect that was not known until the accident. The leading edge scarf joint was out of allignment just enough that when the lightning stuck the blade it caused an arc from the scarf joint to the spar. The arc put a weak spot in the spar that subsequently caused its failure. Since that kind of defect in manufacturing would be difficult to determine in the field, the decision was made to withdraw any blades that had been stuck by lightning.

The blade in question had been sent back to Sikorsky for inspection....and despite that....the defect was not found. Thus, as you point out....very hard to find not only in the field but also at the builder's facility as well.

The fact almost every other dynamic component had been binned from the aircraft with the lightning strike should have been considered much more strongly than it was when it was decided to re-use the fatal blade. But...that is another story as they say.

The S76 lightning strike I was referring to was not the BHL S76 fatal accident, this occurred later. The "accident" in the OGP stats was a straightforward lightning strike, after which the aircraft continued it's flight back to base. During the subsequent maintenance inspection the 'current path' resulted in most of the drivetrain being removed for inspection/repair at major cost.

VL,

We are talking the same two events.

Your contention is the first one (the lightning strike itself) should not have been classified as an "accident" the way I read your post.

Do you base your comment upon the definition of an "accident" under the CAA/JAR/EASA rules and definition they contain for what an "accident" is?

From the CAA Mandatory Reporting Scheme....CAP 382 of March this year

The OGP stats are clearly marked as defining accidents based on the state of occurrences definition of accidents, so the inherent slackness in the US is accepted and that suits some oil companies.

In practice what also happens is that many nations either don't acknowledge accidents when they occur or even issue reports. Thats why the better oil companies are quick to stage investigations themselves for the greater good.

Seems the industry itself likes the "slackness".

I don't see much difference in the US method of defining an accident except the NTSB does break accidents into four categories.

As I wrote, just a few days when I posted that exact link:

The big difference is that aircraft that ditch in the GOM are not counted as having had an accident as though sinking is a normal part of a flight!

SASless you said No. The S76 lightning strike I was referring to had no connection to the S76 blade that failed i.e. different aircraft, different blades.

The point I was making was that accidents that are clearly accidents in the GOM are not captured in the OGP statistics. This is mainly because these particular accidents occur when the aircraft isn't carrying passengers, even though the oil company has chartered the aircraft and pays for the positioning which under "normal" rules is still CAT. They use the fact that the positioning occurs under a different FAR regulation so discount it as a recordable event, even when the pilot perishes.

Shell and other OGP members seem happy to play this game.

Are either of these two aircraft and the related incidents connected to the event you are referring to by chance?




S-76 rotor blades put under scrutiny | Aviation International News

************************************************************ ********************
** Notice created 12/2/2011 Notice 1 **
************************************************************ ********************

IDENTIFICATION
Regis#: 435PH Make/Model: B407 Description: Bell 407
Date: 12/01/2011 Time: 1800

Event Type: Incident Highest Injury: None Mid Air: N Missing: N
Damage: Unknown

LOCATION
City: BATON ROUGE State: LA Country: US

DESCRIPTION

N435PH BELL407 ROTORCRAFT AUTO-ROTATED INTO THE WATER AND ROLLED OVER, GULF OF MEXICO, LA

INJURY DATA Total Fatal: 0
# Crew: 1 Fat: 0 Ser: 0 Min: 0 Unk: 1
# Pass: 0 Fat: 0 Ser: 0 Min: 0 Unk:
# Grnd: Fat: 0 Ser: 0 Min: 0 Unk:


OTHER DATA

Activity: Business Phase: Landing Operation: OTHER

FAA FSDO: BATON ROUGE, LA (SW03) Entry date: 12/02/2011

No, I will try and find the actual event if I can ;)

NTSB Identification: CEN12IA096
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Incident occurred Thursday, December 01, 2011 in Gulf Of Mexico, GM
Aircraft: BELL HELICOPTER TEXTRON CANADA 407, registration: N435PH
Injuries: 2 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On December 1, 2011, about 1005 central standard time, a Bell 407 helicopter, N435PH, was successfully autorotated to the water following a loss of engine power while in cruise flight over the Gulf of Mexico. The helicopter was not damaged during the on water landing. The commercial pilot, and sole passenger, were not injured. The helicopter was registered to and operated by PHI, Inc., under the provisions of 14 Code of Federal Regulations Part 135 as a non-scheduled air-taxi flight. Visual meteorological conditions prevailed and a company flight plan had been filed. The flight originated from platform EC278-C, and was en route to platform EC261, both in the Gulf Of Mexico.

According to the pilot, while en route to EC261 the engine chip light illuminated. The flight was abeam platform EC278-B at the time, and the pilot elected to divert for a precautionary landing. While on the base leg to EC278-B, the pilot heard a loud whining noise followed by a loud popping noise and the helicopter began to yaw. The pilot entered an autorotation, called mayday, inflated the floats, and performed a successful water landing. The pilot and passenger were able to exit the helicopter unassisted into a life raft and were picked up within 10 minutes. The helicopter remained upright for approximately 20 minutes before overturning.

Any info or opinions as to whether this engine failure is related to the no. 2 compressor bearing failures discussed in an earlier B407 thread?

forced landing - no big deal....
 

another reason not to bother having a pointless spare engine

the consequences need to be much worse than this to justify the unreliability of two engines.... mathematically speaking

AnFI you epitomise the poor and cavalier safety culture that permeates the GOM.

SM....you living in a glass house and chucking rocks again! Shame on you!

I am not often with SM but I am this time. This ditching was luckily uneventful but it could have been different.

How the GOM claims to want to improve safety but continues to tolerate ditchings from simple engine problems is baffling.

Beaudreaux done it this way since the very first days using Bell 47's....and Boudreaux don't like change especially if it costs him money. As long as the customers want to do it cheap, and the operators will do it cheap, then cheap is the way it shall be done.

Why just think how much the price of gasoline would go up if all the helicopters in the GOM were twin engined and able to fly around on just one engine?

On the other hand....it is awfully green to fly singles....far smaller carbon footprint and that should make any Greener happy! After all....humans are of a lesser importance than the enviornment.

The way to change this single engine mentality in the GOM is to have the EPA raise the Penalties for polluting the water with all that Jet Fuel and Oils the helicopters put into the water when they ditch, roll over, and sink.

Speaking of twin engines, statistics and safety, the helicopter community has been kicking this around for decades. We are now informed that twin engine commercial airlines can soon take the north pole route. As much as five hours away from a safe landing field on one engine. Was is Disraeli or Mark Twain that said there are lies, damn lies and statistics? Welcome Aboard!

....except the 'papers' forgot we have been running the NP route for decades, I was a very young SLF in 1977 flying from CPH to ANC with SAS and the NP was one of the waypoints. What they meant to say was South (same, same, but different as they say here) Pole. 330 minutes on one engine at MCT, I'm glad it's the cripple seven which was approved and not the scare bus.

TOD

(I'm too old to get into the helicopter with one or two engine argument - I just know which I prefer!)

js0798,

...and that is because the probability of one failure followed by a second from an unconnected cause ('a' followed by 'b') is 1 x 10**-10.

The issue, conveniently forgotten by AnFI, is not the probability of an engine failure – which remains constant at about 1 x 10**-5/hour - but the consequence of a failure if it occurs over a hostile environment (a hostile environment is where safe-forced-landing cannot be carried out – i.e. resulting in a catastrophic event).

What in fact is being advocated by js0798 is not flying a twin over the NP, but a single.

The statistics have not changed;they are just conveniently ignored whenever it suits for the purpose of recycling the argument.

... mathematically speaking!

Jim

Now to refresh and old story about the FAA, Three Engined 727's, over-water flight, and life rafts/life jackets and statistics.

The FAA nodded to Eastern's solicitation to do away with overwater flight required flotation gear for flights between NYC and MIA as the over water portion was a short time and not all that far offshore. With permission granted....Eastern removed all the extra weight of the floation gear.

Less than two weeks later....a FE managed to starve all three engines of fuel...caused all three engines to fail nearly simultaneously...smack dab in the middle of the overwater portion of the flight.

The Crew was able to sort out the situation...restarted the engines...and only got a close look at the Oggin.

The over water gear went back into the aircraft....and I would suppose the FE got the ass kicking of his life shortly after landing!

Statistics are just that statistics....the probability of a second engine failure immediately following the failure of the other engine is only a guess and not a guarantee. They are independent events. There is no guarantee an engine will last more than 30 seconds after installation or that it will go to TBO. Five hours is a very long time to be hanging on one Donk in something like an Air Bus or Boeing with hundreds of folks wondering about how they have lived their lives and wondering about the final tally!

When the first Donk dies.....you are now rolling the dice big time....each second that goes by is another roll of the dice. I like to hedge my bets so I don't lose everything.

There is no such thing as too much power...too many engines....too much fuel.

And then there was the Canadian Airbus that ran out of fuel and did a dead stick landing in the Azores.


Actually, while we are on the subject of safety and statistics, I would like to mention survival gear and the GOM. I'm aware that in the North Sea and Canada, amoung other northern enviroments, survuval suits are required for passengers and crew. In the GOM you may have only a handful of days where the temperatures are below freezing, so there you are - statistically speaking - its not worth the cost or effort to equip everyone with a survival suit.

Back in the 70's flying 206's and looking at the white caps and the cold temperatures, I remembered an article I read in an offshore publication about a hypotheria study done by the University of Vancouver. As a result of that study, they developed a cold water jacket for just such occasions. After some effort, I bought a Thermal Float Jacket from Mustang Sportswear and either wore it or carried it with me for years when it was cold- until I, sort of, outgrew it.

Like SAS says statistics are a crap shoot.

JS,

It is not so much the air temperature but the water temp that creates the real hazard...as water is a much better remover of body heat than air.

Add in the wind to arrive at a chill factor and air temp can be an issue as well.

Now that the rigs are much further out in the GOM...and flying shuts down just a half hour before dark for single engined helicopters....one might be a very long way from help and thus be confronted with a survival situation that includes darkness, a bit of sea state, cold air and cold water....and if not in a raft...it could be a very cold night.

I will bet there are far more periods of time an exposure suit is needed than currently thought, if an honest review of the situation was done.

But then I love the comment...."statistically it is not worth equipping Pilots/Pax with suits!"

Survival Suits - Yes or No
 

There are some very simple answers to that question:-

If 'Time-to-Rescue' is longer than worst case 'Survival-Time' = Yes

(just ask those that maintain that the reverse is the case to prove it with a realistic exercise or two).

If the hazards associated with heat-stress (for the pilots) are greater than the risk of a ditching scenario = No.

The remedy that seems appropriate is that in normal summer conditions during daylight hours (flight completed in daylight) then a survival suit may not be worn. During winter and/or stormy conditions or when any portion of he flight is at night then a suit is to be recommended.

In Europe where the concept of 'Duty of Care' exists the employer would have to demonstrate that to supply additional safety equipment would involve the employer in 'unreasonable additional costs'. It is difficult for any multi-million dollar company to cry 'foul' at a $1000 investment per employee.

G.

Four incidents of interest
 

Azores Deadstick Landing Report REleased - Air Transat

Gimli Glider - Wikipedia, the free encyclopedia

British Airways Flight 9 - Wikipedia, the free encyclopedia

Air France 447 Flight-Data Recorder Transcript - What Really Happened Aboard Air France 447 - Popular Mechanics

The article from popular mechanics is disturbing but very accurate

Cheers

Of course there are some causes which would cause a multiple engine out condition, poor fuel, volcanic ash etc.

However, statistically any engine is likely to suffer a malfunction induced failure before a multi engine out condition is caused by an environmental factor or an incident like the one that happened to Air Transat.

The fact remains that a single engine failure leading to an autorotation and water landing in the GOM is not actually that uncommon. Add some wind, no survival suits, winter, close to the end of daylight etc and you have several "escalation" factors, all of which could be mitigated by the use of twin engined helicopters.

In my earlier post I had pointed out (now emphasized) that the discussion was about engine failures due to unconnected causes – all the cases that have been referenced since were failures due to connected causes.

As Geoff has pointed out, hostility exists when the rescue time exceeds the survival time under the prevailing conditions. Here is a case in point:
Where transient hostile conditions obtain, the operator (or oil company) has a duty of care to ensure that the Risk is Managed using ‘adverse weather policy’ - all the precursors were there.

There was a ‘reasonably probable’ expectation (R=1 x 10xx-5 per flight hour) that this engine would fail.

Jim

Assuming they are loaded to a weight that allows for continued flight following failure of one of the engines.

The BO-105's of an Operator sometimes did not meet that commonsense idea....and at least one of their aircraft DITCHED following an engine failure in the cruise portion of the flight returning ashore.

Remember this is the helicopter industry segment that at one time went ten years without granting a "Cost of Living" pay raise to its Pilots.

Cheap is a God down there.....and is worshipped religiously!

Better and cheaper than using a twin would be just not making the flight. There are boats available, and it's not that long a trip, but most of the passengers I've ever carried would prefer the helicopter over the boat, regardless of the risks.

That was a PHI Bo105 on contract to Shell Oil.:ugh:

After that a series of Brits were seconded into Shell Oil to get a grip.

Presumably you were one of the high and mighty, hypocritical, know-it-alls who were amongst them? You really do nothing for Brits if that's the case and just make them hated the world over, which is why all Americans so loved the oil spill of another 'Brit' company recently. Now, preach to us all about oil spills, Nigeria, pollution of the environment, lack of any credible maintenance and safety culture until indigenous people's environment was polluted for 30+ years, corporate complicity in political murder and then let's talk about Shell's wonderful safety culture :mad:

Sure SAS, the weight and balance issue goes without saying. But I refer really to the newer generation of twins that actually do have some OEI capability. I would not call a BO 105 or a 355F a twin for example because neither really have any credible twin performance.

... some thoughts
 

- not at all.

Because It is not correct or relevant to use Lookup Sir Roy Meadows and what the Royal Statistical Society thought of the use of the same statistic.

Jim - what figure would you put on 'a' following 'b'?
is it in the order of 1in10?
rather than 1 in 100,000?


Would you also agree with me that it's not the risk of forced landing through the 'engine failure' cause but any cause which needs to be factored in?

So:

The other risks from having 2 engines should also be factored in. ie:
the risk of running a complex gearbox (Rgb)
the risk from running all the critical components to a higher load than would be
the risk of major destructive Eng failure etc.


The accidents we see, demonstrate that 1x10^-10 is not relevant.

Also the 'fatalness' of the hostile environment needs attention. You are using the consequence of failure in a hostile area as P=1 , all I was pointing out is that
Risk of death in ditching in GOM? 0.1? 0.01?
it is mathematically speaking much easier to do something about that sized number than a number already this small - 0.0000001

People are generally not good at estimating risk.
Do you carry a knife when you carry a dingy in the cockpit?

Anfi, Jim quite clearly stated that the risk of an unconnected second engine failure (he even underlined it himself) used the square rule, whereas in the Meadows case the second death could not be considered unconnected as both babies were genetically and environmentally linked. One could say that this is analagous to a twin engine installation, however the whole purpose of the Cat A certification standards is to try and remove that 'environmental link' so far as is possible though isolation and protection features.

Most twin engined helicopters today have EFIS, Autopilots, EGPWS, TCAS and FADECs, are certified for IFR and are operated two crew. Within that list, there is plenty to reduce the risk of an accident from causes more common than engine failure, and most of those items are not present in a single!

One must also remember that there are other reasons to end up on one engine in a twin, beside a straight forward failure - such as chip lights, fire warnings etc - and in fact you may have one engine at idle rather than shutdown. Better to carry out a precautionary shutdown (or retard a throttle) and head home, rather than ditch - surely!

AnFI,

Let's deal with the engine failure first: it has been established (empirically) that the failure rate of helicopter (turbine) engines is about 1:100,000/flight hour. When two engines are fitted, and certificated, the rules require that each engine is protected (to the extent possible) from failure of the other.

If we exclude failure from (common) external factors such as salt water ingestion, ash ingestions, fuel starvation, FOD ingestion etc., we can assume the failure of each engine is an independent event. The probability of an engine failure is 1:100,000 (or 1 x 10^-5) therefore the failure of one engine followed by the failure of the other is 1 x 10^-5 and (times) 1 x 10^-5 or 1 x 10^-10.

Hence the probability of failure of 'a' followed by 'b' is 1 x 10^-10.

The result of an engine failure for a single is a forced landing; the result of an engine failure for a CAT A twin operating in Performance Class 1 is continued flight on the other engine.

However, the important issue is the consequence of the failure; if we assume superior skill in the pilot performing an auto-rotation and landing, what remains is the characteristic of the (forced) landing site. If the landing can be performed without harm to the occupants of the helicopter it is said to be a safe-forced-landing. Where the landing cannot be performed without harm to the occupants of the helicopter, it is said to be hostile.

Hostility is ICAO is defined as:
Clearly: b) above can be mitigated with the use of life-vests (with splash hoods), life-rafts and survival suits; c) is dependent upon b) and the efficacy of search and rescue.

Where hostility of the environment is transient - i.e. at sea - but occurs frequently or can happen very quickly, some States take the precaution of defining it as hostile.

Where hostility of the environment is transient but occurs infrequently and with warning, the operator is left with the Risk Assessment and provision of appropriate 'adverse weather' policy/procedures.

As you have said, there are other reliability issues that have to be addressed; these are dealt with in certification and build standards, and component lifing; or, with redundancy. Some States also take the additional precaution of permitting flight over a hostile environment only in Performance Class 1 (certification in Category A being a more quantitative process).

All of this has been considered in detail for a number of decades; States and operators (and oil companies) have used the above tools to Risk Assess their operations and make appropriate provisions in their regulations/procedures.

It all comes down to the old adage, horses for courses.

This is not a single v twin but a risk assessment discussion. Mathematics /statistics /probability just provides us with the tools with which to make the best (and informed) decisions.

Jim

Horses for courses...
 

Sure its a risk/consequence calculation where correct use of statistics are a tool - but you know what they say about statistics !

You say - That is TRUE - BUT we can't - we can pretend/reduce/try/hope etc but we cannot render POWER delivery independent - Especially if they share a common drive chain - where the risk of combiner gearbox etc etc must be factored in.

We expect the engine to deliver a POWER LEVEL (OEI30secs or OEI 2:30) which it has not regularly been tested to - it is being expected to do that because one engine has failed. An engine that it has probably shared a history with (same manufacturing batch, same unaccounted for running on rocket fuel in Bongo-Bongoland? etc..)

Pilot's close down the wrong engine - extinguish the good one etc - many factors which come in at significantly greater than a compounded 1x10^-5,

If it really were 1x10^-10 then we would never see the examples we do - so we can see it is not correct 'by inspection'.

We might want to but we cannot fairly just compound 1x10^-5 and use that figure - other than very hypothetically.

Also the INCREASED risks you refer to: Well it's really not fair to hide them out of the equation - they are the price paid for the (hypothetical) 1x10^-10
And many of those standards (dual hydraulics) - chickens in tail rotors(?) etc are equally applicable to singles....


The negating of Hostility by mitigation looks like it has merit especially wrt ditching survivability - any controlled arrival into any water state should/could be rendered survivable - surely? (is that true?)

If the probability of arriving in the water were truly only 1x10^-10 (which it is not) then that is SO small that carriage of floatation equipment would not be required/safer, the risk could possibly be higher....

It is surely flawed to make risk from one specific cause (engine) better without including the increased risk from other causes - (like the tail boom falling off etc etc ...)

Nick Lappos has/had a really excellent arguement about 'over-engined twins' wasting payload on an almost irrelevant slice of 'exposure' during the Take-Off/Landing Phase - he wrote an excellent article on it - (somewhere?)

I am not against TWINs - and agree with Jim that it:
So it's perfectly fair and reasonable that manufacturers should be free to supply the free market with whatever hair brained scheme their engineering ingenuity comes up with to deliver the safety outcome the market demands - even if it means fitting two engines - or floating saftey cell cabins - to make the safest product ... dubious maths should not be enshrined in law to dictate particular engineering solutions.

Although I suppose it helps push the manufactures along....

Customers / oil companies / police forces should be free to demonstrate their commitment to safety by procuring helicopters which their consultants believe are safer...
it's a very strong driver.

Do you really want to be up an Alp in an EC145 in preference to a B3(e?) ?

Power / capability / reliability / margin or accountability .... ?
One saves pilots/people the other saves ..... accountable managers.

Patrick Goudou (EASA) doesn't have time to consider this topic:
Opinion04-2011

Jim has done a great job of forcing some rational considerations up the flag pole and into law - but isn't it time we 'upped the game' and lent a bit of support in the same way to other solutions... are there any aircraft designers out there who can clarify the mathematics?

JimL, 212man,

your efforts to have a rational and well-thought-out discussion with AnFI are mispremised sadly: Following the onerous and quite pointless "loss of visual references diatribe", it seems he has a new stick to beat and will go on talking rot as long as someone is prepared to engage with him.

An FI. You are offshore and have one engine and experience a failure. What will happen next? Get a grip man.

TT: Trick question, right?
 

Relax, land gently, go boating - enjoy!

TT: You're onshore, CatA PC1, could auto easily if required, your tail boom falls off. What will happen next?


it is just not 1x10^-10 - is it?