Monday, October 31, 2011

Comments, questions, stories

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In this world we are all friends.

LAF and BAF Part 3.

LAF and BAF Part 3.

And so we look at BAF.

BAF, or ‘Big Aeroplane Fuel’ as we have come to know it, is paraffin. Or, if you prefer, kerosene.

Why do we use it in big aeroplanes?

The flame rate is slower at only a few feet per second. It is harder to light and easier to extinguish. The energy content is acceptable at (Jet A-1) 43.15 MJ/kg (1 MJ/kg = 430 Btu/lb so about 18,500 Btu/lb.).

Aviation turbine fuel (Avtur) is commonly known in commercial circles as Jet A-1. There is also a Jet B. And a gasoline based jet fuel called Avtag.

Let’s look at some fuels that are kerosene jet fuels:

JET A         A kerosene type fuel with a freezing point around -40°C. It is available only in the U.S.A.
SG Range = 0·775 to 0·83

JET A1         See below

JET B         This is a wide range distillate known as a wide cut gasoline. Not in common use. It is a Naphtha based fuel used primarily for low temperature conditions.
SG Range = around 0·76.

JP 4         This is a wide range distillate known as a wide cut gasoline. When certain additives are present it may be known as AVTAG. For military use.
SG Range = around 0·76

JP 5         High flash point kerosene mainly for aircraft carrier use. May be known as AVCAT.
SG Range = around 0·83


FLASH POINT                           38°C Minimum

SPECIFIC GRAVITY                  0·81 at 15°C

CALORIFIC GRAVITY                  18,560 BThU/lb OR 150,400 BThU/gallon

VISCOSITY-         from 22 Centistokes at -60°C to 1·2 Centistokes at +43°C

FREEZING TEMPERATURE         -40°C maximum.

Note: When kerosene freezes it forms a sort of sludge.  Really, it is the water in it that is freezing and not the kerosene itself. Diesel does a similar thing that we call ‘waxing’.


Well, OK.

Kerosene, in common with other hydrocarbon fuels, is hygroscopic. That means it loves water. It will soak up water until the water begins to coalesce. Major problem now. That water will form droplets in the tank that becomes larger pools. The water that goes down the feed line to the engine can cause flameout and the water that remains causes corrosion in two ways:
1.   By direct contact with the metal walls of the tank and,
2.   By promoting the growth of fungus.

Unlike gasolines, kerosenes all have microbial spores in them. If the temperature is satisfactory for it and if there is water present then these spores will hatch out into fungal growths.

Believe me, this fungus smells really, really bad. It also blocks filters, and pipelines as well as causing corrosion.

Another problem is that the fuel, in rolling around in the tank because of aircraft manoeuvres, will rub on itself creating friction that, in turn, creates static electricity. If there is one part of the fuel at a low level of electrical charge and another portion that is at a high state of charge then there will be lightning in the tank.

This is a bad thing.

To prevent this an additive is put in the fuel to make it electrically conductive. There are also other additives to prevent icing, to prevent fungus growing (biocidal additives) and lubricity additives to stop the pumps and things burning out.

These fuels are very well engineered, are they not?

Some general thoughts.

All fuels are toxic. If you are going into a tank that has had any fuel in it then you need to vent the tank thoroughly.
You also need a medical check before going in or there may be insurance problems in the event of a disaster.
Once the tank has vented remember that there will always be loose (wet) fuel somewhere that is sneaking up on you as vapour.
Measure, and monitor, the lower explosive limit all the time. If the tank is below 25% of the LEL you may go in with breathing apparatus. Below 5% LEL you can remove the breathing kit –but beware that it doesn’t sneak up while you are in there.

Make sure the safety person is strong enough to get you out if you become unconscious!
Make sure that you do all the talking so that the safety person knows you are all right!

If you get fuel on you—wash with cold water FIRST! Then wash with hot water.
Hot water opens the pores (little holes) in your skin and that lets the fuel into your body.

Now you know.  BAF and LAF should never, ever be mixed up. Disasters have happened due to the refuelling of Big Aeroplanes with LAF and Little Aeroplanes with BAF.

Don’t let it happen to you!

BAF and LAF Part 2

Let’s start with LAF.
No particular reason other than it’s my ‘Blog’ and I choose to start with LAF. OK?

LAF is short for ‘Little Aeroplane Fuel’ and is petrol. Also known in some, less developed, parts as ‘gasoline’. For this reason the petrol they put in aeroplanes is known as AvGas.
AvGas is ‘Aviation Gasoline’.
AvGas is very similar to the stuff you put in your car to make it go—unless your car runs on diesel or NGV in which case it is very different.
Putting petrol in aeroplanes gives several problems.
Let’s start with the idea that as you ascend up Mount Everest the boiling point of your water is going down. By the time you get to the summit your water will boil off by pouring some in your hand.
Similarly, the water in your car radiator will not boil until it gets to 110°C, or thereabouts, because the radiator and cooling system is pressurised.
This change in boiling point is all due to the different pressures on the surface of the water.
To say that water boils at 100°C is only true if we add “at ISA SL” atmospheric pressure.
Note: ISA SL = International Standard Atmosphere at Sea Level.

Caution: If you remove the cap from the radiator of a hot engine the pressure on the coolant will suddenly reduce—thus lowering the boiling point dramatically. Equally dramatically, every molecule of coolant will now wish to turn to vapour, which will cause it to occupy a much greater space. Since there is no more space in its immediate surroundings the only place it can move to is outside the system that contains it. It will do this by attempting to pass through the hole that you have just made.
Result? A jet of superheated steam in excess of 100°C will now come out of the radiator filling hole at huge velocities. Contact with your skin will scald the skin and the velocity of the escaping gas will rip it off.
Important to know this, isn’t it?

Note: The boiling point of a substance is the temperature at which it can change state from a liquid to a gas throughout the bulk of the liquid.

Now let’s think about petrol. Petrol is lighter than water. It evolves into vapour more readily than water. Its boiling point is lower than water (95°C at ISA SL). Like water, the boiling point will reduce with altitude.
Aeroplanes fly higher than Mount Everest but, in World War Two, the American high level bombers, flying lower than Mount Everest, were losing up to 10% (Ten Per Cent!!!) of their fuel load because the gasoline was boiling off—it was turning into vapour.
Although the figures will vary considerably we could say that the RVP (Reid Vapour Pressure) for petrol is around 10-12psi.
So what is RVP?
Reid Vapour Pressure is defined as the absolute vapor pressure exerted by a liquid at 100 °F (37.8 °C) as determined by the test method ASTM-D-323.
What does this mean in practical terms?
There is a surface pressure at which hydrocarbon fuels will begin turning to vapour at a specific fuel temperature. Of course, gasoline and other fuels will vaporise over a period of time at any pressure and temperature but there comes a point at which vapour evolution is critical and measurable because of the reduction in boiling point.
The cure? Pressurise the fuel storage system (fuel tanks). This may create a heavier structure and a complex system to control it—also heavier.

What other problems are there?

In the old days there were lots of different petrols (Avgas) available. They were engineered to tolerate different compression ratios.
This leads us straight into a triumvirate of conditions.
Piston engines that use gasoline all operate as a ‘Modified Otto Cycle’ They are four stroke (for the most part) engines. The four strokes are:
1.             Induction. The piston moves down to allow a fresh mixture (fuel and air) into the cylinder head.
2.            Compression. The piston moves upwards to increase the pressure on the mixture.
3.            Power. Just before the piston reaches the top of the compression stroke there will be a spark to ignite the mixture. The burning mixture now adds heat energy to the system at constant volume. The increase in pressure moves the piston down on the power stroke.
4.            Exhaust. The piston moves back up to allow the burnt gases out of the cylinder head, thus making room for fresh mixture.
At 3,000 rpm each stroke takes 1/50th of a second. Not much time, then.
Gasoline vapour burns at about 100’ (feet) per second. It takes time to burn and more time to transfer the heat to the air and then the air needs time to expand.
This is why the spark has to be before the piston gets to the top, to allow for a delay in the burning, transfer of heat, expansion in the cylinder head.
Another factor is mixture strength.
Complicated, isn’t it?
The stoichiometric ratio (sorry about that!) for gasoline is 14.6:1 (Natural Gas and Diesel are about 14.5:1; compare with Hydrogen at 34.3:1.).

Note: A stoichiometric ratio is the ratio at which all the fuel and all the available oxygen are completely burnt. A perfect mixture, if you like.

So you have 14.6 parts of oxygen and 1 part of fuel vapour. It will now burn nicely.
About 12:1 will also burn but that is called a ‘rich’ mixture. You are leaving a trail of black smoke (unburnt fuel turns to carbon as opposed to oil that burns blue-ish or white). A weak mixture extreme might be around 17:1. We like to burn a tiny bit weak because that saves us money on fuel but too weak creates a hole in the piston, valves and our bank account.

So what if we have a high compression ratio, a weak mixture and an advanced ignition?
Whoa? A what?
The faster that an engine is running the less time there is for the fuel to burn. For this reason the spark needs to be initiated even earlier. Then, as the rpm of the engine reduces, the spark can be moved closer to TDC (Top Dead Centre—the point where the piston changes direction at the top of the cylinder as opposed to BDC—Bottom Dead Centre which is the same thing at the other end of the piston’s travel).
Moving the spark away from TDC is advancing the ignition and moving it back towards TDC is retarding the ignition.
If we advance the spark too far the air will expand and push down on the piston too soon. We need this maximum pressure—called BMEP (Brake Mean Effective Pressure), around 22° after TDC for best results.
Too soon and the mixture in the cylinder head will cease to burn rapidly and will, instead, explode. This is called detonation or ‘pinking’ or ‘knocking’. It is very damaging to the engine.
Aero Piston engines needed increased compression ratios to develop more and more power. This increase in CR (Compression Ratio) creates a higher possibility of having detonation.

Note: Many piston engines have bimetal washers under the cylinder head wired to a gauge. This acts as a temperature sensor. A sudden increase in cylinder head temperature indicates that detonation is occurring.

Petrol is engineered to deal with detonation—up to a point.
Most petrols have an ‘octane’ rating. For your car it will be either 95 or 97.
For aeroplanes it is normally, now, 100LL.
The octane rating of petrol was increased by the addition of Tetra Ethyl Lead. This is a bad thing.
Now it is done with other additives and hence we have 100LL or 100 Low Lead.
An octane rating is found by increasing the compression ratio of an engine using the fuel at a specified mixture strength until detonation occurs and then comparing it with an iso-octane fuel. The 95 or 97 is a percentage of that figure—the iso-octane is always 100%.
You cannot get more than 100% so a higher number will be a ‘Performance Number’ and not an octane rating.

100/130 AvGas, now commonly called Avgas 100, is dyed green. 100LL has replaced 100/130 in most places, but AvGas 100/130 is still sold in Australia and New Zealand, I’m told.
In the past other grades were also available particularly for military use, such as AvGas 115/145 (dyed purple) and 91/96 (dyed brown).
Limited batches of 115/145, commonly called AvGas 115, are produced for special events such as unlimited air races; in the past 115/145 was used as the primary fuel for radial engines.
The second number is the Performance Number at ‘Rich Mixture’ conditions. On most of these engines the mixture strength can be adjusted for ‘warm up’, acceleration (Take off) and ‘Economical Cruise’.

So now you see that Little Aeroplane Fuel is quite complicated.  You should also note that it catches fire more easily and is more difficult to extinguish than BAF. It is also more expensive.

We shall look at BAF in Part 3.

BAF & LAF Part 1.

A short while ago I was asked, in passing, if the ‘petrol’ used by aeroplanes is all the same.
The answer to this is ‘no’. It is not.
And so we move on.

The subject this time is BAF and LAF.
You want to know, don’t you? I can tell.

BAF = Big Aeroplane Fuel
LAF = Little Aeroplane Fuel

Way, way back in the early days before even I was born—yes, yes, there was such a time, all aeroplanes used LAF.
Then, just after the Second World War, little aeroplanes used BAF until the de Havilland Comet was invented. Aaaah! De Havilland! A thing of grace and beauty that swung effortlessly into the air assisted by angels and four de Havilland Ghost engines on the 27th July, 1949. BOAC started services with the Comet 1 in May, 1952.
Note: the Boeing 707 was not invented until 1955.
Up until the Comet and the 707 (720, according to United Airlines) all big aeroplanes used LAF. Most little aeroplanes were now using BAF
These little aeroplanes were Hawker Hunters, Supermarine Swifts, Fairey Gannets and the like.
Some mid-sized aeroplanes like Vickers Viscounts, F27 Friendships and Dart Heralds were also using BAF.
In the sixties and seventies a swarm of big aeroplanes took over commercial flying that were equipped with magical engines called ‘gas turbines’—jet engines, that were more powerful, more economical, more reliable, quieter (inside the aeroplane) and smoother than the old piston engines.
Suddenly the world had changed. Suddenly the world could afford to fly. The airways as the province of the wealthy and famous was gone.
There are still some hangovers from those days. To cross large bodies of water you still need to have more than two engines—that led to the development of a host of three-engined aircraft like the Lockheed Tristar, BAe Trident, Douglas DC10.
Big aeroplanes now use BAF and little aeroplanes use LAF except that there are still some preserved, old aeroplanes that are big and use LAF and, of course, there are a few little aeroplanes that use BAF.
There will always be delusions if grandeur amongst the smaller ones!

Now we shall look at what BAF and LAF is.

Monday, August 22, 2011

The Great Step Forward

Going over some old thoughts the other day.  Pondering, as it were, the way jet engines have changed over the years.
No change in the basic theory, of course, but a lot of refinements and improvements in materials.
Of course, the manufacturers have put in a lot of effort to fine tune engines and improve gas flows and aerodynamics—especially in the turbine but there has been one thing that, to my mind, was the real turning point.  That moment in time when jet engines ‘grew up’.

Before I get into that, let’s just think about the ‘old days’ of  gas turbines.  Aero-gas turbines as opposed to hulking great industrial LP gas turbines with, or without, closed loop systems as made by the likes of Solar and ASEA Brown Boveri.

[NB: The Solar Saturn engine, first designed in 1950 for the US Navy and produced in 1960, went on to become the world's most widely used industrial gas turbine with some 4800 units in 80 countries. It remains in production today in two up-rated and enhanced configurations.]

Our good old ‘clunky’ engines were highly reliable and ruggedly built, for the most part.  They were pretty heavy for their thrust output but the idea was to contain all that heat and energy.
Of course, many of the old engines were centrifugal flow.  The wonderful sounding Derwent, Ghost, Goblin were all centrifugal flow as were the first turbopropellers—chief among them being the redoubtable Dart, still in use today.  First produced in the late 1940s, it powered the first Vickers Viscount maiden flight in 1948, and was still in production until the last F27s and H.S 748s were produced in 1987.
These centrifugal flow engines were very robust and had very simple systems; the fuel system on the Dart is a model of simplicity.

“Whittle… stressed the great simplicity of his engine. Hives [Director of Rolls Royce] commented, ‘We’ll soon design the bloody simplicity out of it.’ ” [From Genesis of the Jet]
How successfully they have achieved that!

Is an interesting web page—especially the early history.]

Of course there were axial flow engines, too.  The Avon, Sapphire, Viper were all axial flow as were many of the early Pratt & Whitney engines.
Some engines were compounded.  The reverse flow Proteus turbopropeller engine had axial flow and a centrifugal last stage to ‘turn’ the air around the corner into the combustion section.  This is still something that is widely used, not least by the wonderful PT6 engine.
All these engines had alloy front ends with aluminised mild steel rear compressor sections and outer combustion casings.  The materials used were fairly standard in those days, the hot parts were various forms of nimonic—‘Hastalloy’, ‘Waspalloy’ (Registered Trade names of ‘Special Metals Group), which is a nickel alloy in various guises.
Materials have moved on.  We still use nimonics in conjunction with crystals for turbine blades but there is increasing use of lighter and stronger metals like titanium.  There is also more use being made of composites here and there on colder parts.

[NB: The ‘colder’ parts are not all ‘cold’.  Remember that the temperature of the gas coming off the compressor of a twin spool engine like a ‘Spey’ is around 550°C which is the same temperature as the glowing end of a cigarette when you suck on the other end.]

So where is the ‘breakthrough?  Is it the multi-spool engine like the JT9D or Spey that led to the Triple Spool RB211—a machine of great beauty and elegance?
Is it the development of high by-pass engines for the military airlift aeroplanes?
No, no.  None of these.
Lets go back to the Viper.
No, really!
The Viper was developed from the Adder engine that was developed, in turn, from the Mamba that came from a Metrovick project.  The twin Mamba was successfully installed in the Gannet and the Adder engine was the prototype Saab Draken engine.
‘Power by the Hour’ leasing was started in those days as the Viper had maintenance issues resulting from it being developed as a limited life engine (10 hours) for the Jindivik target drone.  Operators would pay a fixed hourly rate to Bristol Siddeley for the continual maintenance of the engines.
There was one major step forward.
But the main one was that these engines had vaporising burners.  Not a big issue.  Vaporising, hockey stick, burners were very efficient but hard to start so atomising burners (4) were used as well to start the engine and get the vaporising burners going.  The atomising burners would remain burning while the engine was running.
How is that a major leap forward?
Because they were in an annular combustion chamber.
Why is that so significant?
This engine, like the constant volume engine and the external combustion engine is a heat cycle machine.  It relies for its effectiveness and operation on the addition of heat energy.
Irrespective of the temperature of the gas coming off the compressor, fuel is burnt in the combustion chamber in order to add (heat) energy to the working fluid (air).
Separate combustion cylinders and can-annular (cannular) systems are limited to the number of burners they can hold and control—in terms of flame shape; this includes multiple burner systems on early Pratt & Whitney engines.
But annular chambers can have as many burners as you can fit in them.  This means you can add as much heat as the engine will take without a disproportionate increase in temperature.

Now, from that, we leap forward.  Old engines ran at 10:1 compression ratios.  It was thought that the maximum possible would be around 20:1 before all sorts of problems occurred.
Now we are running at over 40:1 compression ratio on a routine basis.  We have high by-pass engines where 80% of the airflow is going down the by-pass duct and doing most of the work and that means that the fan is being driven by 20% of the airflow in a small core engine.
Huge amounts of power are generated in the core turbine to drive the big fans which means that the pressure ratios must be higher, the temperatures are higher, the stresses are higher.
All this is possible because the amount of heat that can be added is exponentially increased by the use of annular combustion chambers

And that, dear friends, is all thanks to Bristol Siddeley and the humble, disposable, Viper engine.

Thursday, August 18, 2011

By 'The Book'

Recently I have been speaking about safety.  I have said, time and again, to the point, no doubt, of boredom, that there is only one way to work on aeroplanes.

The right way.

Is 'The Book' always right?  How often have you read an entry in the Aircraft Maintenance Manual (AMM) and wondered if there could be a 'better way'?

Rarely, one hopes.  If you analyse 'your way' you may, very often, find that there is a flaw in your analysis or sequence of events for a particular task.

Sometimes events occur that highlight a flaw in the system.  A system that we have, hitherto, considered flawless.

The NTSB (National Transportation Safety Board in the United States) has written a letter to the FAA (Federal Aviation Administration) pointing out something that should have been obvious from the very start of commercial aviation and yet...

This is very well worth reading, it will take a few minutes of your valuable time but make the effort.

We are not only concerned with what it is saying about this specific point but also we should consider the ramifications on everything else that we do.

Next time you work on an aeroplane  -  and by 'work' I am not just referring to maintenance people (wonderful souls though we undeniably are) but to flight crews, cabin crews, baggage handlers, catering delivery people, fuel tanker drivers, etc., and say to yourselves, "Am I missing something obvious?  Is what I am doing safe?  Is it safe for me, for the aeroplane, for other people?"


Flying is, inherently, safe.  Modern aircraft design and materials make it so.  Humans working on it reduce that level of security.

Working to 'The Book' should prevent that reduction.


Does it?

Tuesday, August 9, 2011

Addendum to "Think Safe"

In the last 'Blog' I have mentioned that there is a rule that every one of my students hears.  This is,
“Rule 1: Look after yourself”.

This is number 1 of “The Three Leyman Laws of Aviation Maintenance”

Let’s have a look at them now while they are fresh in the mind and applicable to the previous ‘Blog’.

Rule 1: Look after yourself.  Only you know what you are doing and why you are doing it.  You are the person best placed to observe and assess the risks and to take the appropriate action to avoid harm to yourself.
If you do not look after yourself then you are not going to be able to obey rule no.2.

Rule 2:  Look after your colleague.  It is eminently possible that the person, or persons, that you work with are not your friends.  It would be nice if this were always so but life being what it is you will find that, sometimes, you will work with someone you dislike.
Fact, you still have to work with them.
Fact, you are still in a team with them.
Fact, they are your colleagues.
Look after them because there may come a time when you need them to look after you.

Rule 3: Look after the equipment.  Much of the equipment used on modern aeroplanes to maintain them is extremely expensive.  Some of it is fairly delicate (ask your avionics people about the TDR – Time Domain Reflectometer!).  Certainly a lot of the equipment on the aeroplane is delicate and expensive – need I mention inertial navigational boxes?
If the equipment becomes defective it will require repair or replacing.  All airlines are pricing to the bone to be competitive, additional repair costs for equipment, especially Ground Servicing Equipment (GSE) could be the straw that broke the camel’s back.
At best you could be looking at a zero pay rise or, at worse, looking for a new job.
Possibly, defective or ill-maintained GSE could cause you injury (have you seen a toe that had a tow-bar - no pun intended, dropped on it?).
Either way, not looking after the equipment contravenes Rule 1 (see above).

Don’t say you weren’t warned!

Think 'SAFE'!

At great risk of sounding boring or repetitive, I should like to say, again, that when one is involved in aviation maintenance there is only one way to do things and that is the right way.
There are no ‘ifs and buts’, there is no negotiation or discussion necessary and there is no such thing as ‘it will do’!
Quite apart from the number of injuries and fatalities to passengers and crews due to aircraft making big black smoking holes in the ground, there are also risks involved with maintaining aeroplanes.
Time and time again I have said to students taking part in all sorts of courses, “Rule 1: Look after yourself.”

Sadly, this advice tends to be disregarded.  Primarily, I suspect, because most people believe that accidents happen to other people, they forget that, to everyone else you are the other person!
On my ‘Facebook’ page [] I have given an example of what happens when the appropriate safety precautions are not taken.  There is also a mention there that two people a year, on average (I am told) are sucked into jet engine intakes.
The number of people who are struck and killed by propellers and tail rotors is significantly higher.

How does this happen?  Why does it happen?

For many years the makers of propellers and various Aviation Authorities – the CAA (UK) not least among them, have attempted to discover the magic paintwork that will show a propeller up even when it is spinning.
They have failed.  Without exception.
The fact is the propellers become invisible when they are rotating at any rpm that becomes inimical to human health (Translates: ‘lethal’).
I spend much time emphasizing to students that if they cannot see a propeller it is very dangerous.  Very.  This was even stated clearly in “A Simple Guide to Understanding Jet Engines” on Page 59 with a sad example given.
The air rushing into a gas turbine intake is also invisible.  There is a famous incident on a US aircraft carrier (USS Theodore Roosevelt, I do believe) where an airman was sucked into an A-6 Intruder intake and survived.  He survived because his helmet came off and smashed the compressor blades before his head arrived on the scene.
He was lucky.  Extremely lucky.  He was also foolhardy.
Propellers and air rushing into intakes are both invisible.  The movement of air from one place to another is unstoppable unless you are aerodynamically shaped to permit the flow of air to slip past.
Most people, however, tend to wear clothes when working.
“A Simple Guide to Understanding Jet Engines” Page 131, qv.

The primary cause of these accidents is somewhat deeper.  It is invisibility and the inability of the human person to fight the movement of air which creates the accident but there is something much more sinister that creates the situation!


We are, all of us, victims of compulsion and impulsion.  Every one of us has pressure applied to do the job quickly.  We understand that aeroplanes only make money when they are flying – on the ground they soak up money like a dry sponge.
There is constant pressure on us all to get the aeroplane back up in the air as quickly as possible, that there are schedules that must be kept.
Combine that with the idea that “familiarity breeds contempt”.
We adopt a laissez faire attitude, a feeling that ‘nothing ever happens’ or that the risk has been overstated (by people like me!).

But accidents happen.

“An Air New Zealand spokeswoman said the engine (RR-Allison T56) was sitting on a stand without propellors (sic) attached and was not affixed to a plane (C-130) at the time of the accident.”
A 51 year-old mechanic was sucked into the intake and died.
It is possible that he did not get ‘chopped up’ but his body, in blocking the intake, created a huge depression that damaged his lungs.  This must have been, necessarily, at low power because the propeller was not installed.
Low power - and yet...
This is a turbopropeller engine that develops around 6000HP.  Low power?  Still significantly higher than your Ford Focus engine!
It has something in common with a Ford Focus  -  it is NOT a toy!

Careless?  Yes.  Should he have known better?  Yes.
Ask yourself ‘how did it happen’?  Try to go through it in your mind.  Ghastly, isn’t it?

Most people believe that accidents happen to other people, they forget that, to everyone else you are the other person!

Monday, May 2, 2011

Wildlife Pt 2

Just in case the article is taken off the 'net before you read it, here is what it says:

Deep sea search parties have found one of two recorders from an Air France flight that crashed off the coast of Brazil in 2009, according to investigators.
The news on Sunday revived hopes of understanding what caused the crash.
The Airbus 330-203 jet fell into the Atlantic Ocean off the northeast coast of Brazil en route to Paris from Rio de Janeiro in June 2009, killing all 228 passengers and crew on board after the flight hit stormy weather.
The flight data recorder (FDR), which stores technical data, could give vital clues about the flight's final moments.
French investigators said in a statement the FDR, which along with the cockpit voice recorder is called a "black box", had been hauled up to the deck of a search boat.
Pictures published on the website of France's BEA air accident inquiry office before the instrument was pulled to the surface show an orange cylindrical object half-buried in sand.
A BEA statement said the "memory unit" was "in good physical condition" after it was "raised and lifted by the Remora 6000 ROV [robot submarine] on board the ship Ile de Sein at 16h40 UTC".

'Good physical condition'
The discovery comes after years of start-and-stop search efforts on a 10,000sq km area of sea floor to locate the aircraft's two recorders, which investigators hope will settle a dispute over the cause of the crash.
Jean-Paul Troadec, the BEA's director, said: "At this stage, the box seems to be in good physical condition. Our experts will tell us if there's hope to read the data.
"If the data can be used it will allow the enquiry to make headway because the FDR records the altitude, speed and the various positions of the rudder."
The FDR was expected to arrive at BEA offices within eight to 10 days, to allow for the search of the cockpit voice recorder, so the two can be taken back to France.
Speculation about what caused the accident has focused on the possible icing up of the aircraft's speed sensors, which seemed to give inconsistent readings before communication was lost.
Investigators announced on Wednesday that search teams had retrieved part of a "black box" from the aircraft but not the part containing the key data.
BEA said the chassis that held one of the recorders was found a day after a salvage ship began working to retrieve bodies and recently discovered wreckage using the Remora submarines.

Previous searches had recovered a limited amount of wreckage and about 50 bodies.
Air France and Airbus - which are being investigated for alleged manslaughter in connection with the crash, the deadliest in the carrier's history - are paying the estimated $12.7 million cost of the search.

Thursday, April 21, 2011

What is NOT Said!

The TV was on this morning, coffee time.  The programme was ‘Air Accident Investigation’.  Seemed good enough to spend an hour watching.  Us aviation type people will watch anything that’s got aeroplanes in it even if it is a little traumatic.

This was a lot traumatic.  This was the story of how two pilots fought a B747 for over thirty minutes, not knowing their efforts were useless.  It was Japan Air Lines (JAL) Flight Number 123.
Dreadful accident.  Just dreadful.
Miraculously there were survivors.  A few.  There might have been more but rescue was late and the mountaintop was cold.

The programme detailed the events that led up to the accident.  It was both enthralling and horrific.
At the end they reported on the cause.  In some detail.  They stopped there.
They did say that there was to have been a prosecution against Boeing but it never came about.  They did say that there were lots of conspiracy-mongers who said that the blame lay with JAL and not Boeing, that JAL was being ‘protected’ by the Japanese Government and Boeing.
Still, JAL very nearly went under because of it.
JAL was entirely innocent.  As innocent as all those victims.
The cause?  A repair to the rear pressure bulkhead had blown apart and removed, in so doing, the fin of the aircraft.  Thus the aircraft had become uncontrollable with the inevitable consequences.

I remember, many years ago, that there was talk about the engineer who had come out to Japan from Boeing to effect this repair.  That it was his fault.  The finger of blame descended upon him and his team.
But let’s just think about that for a moment.
This is a skilled engineer and his colleagues.  They are all experienced and know the B747 well.  They know their job well.  These are good people at the top of their profession or they would not have been sent out to Japan to do this work.

Shall we go back to the beginning?  This B747 made an appalling landing, for reasons best known at the time to the pilot alone.  He managed to skid the empennage along the ground causing damage to the under-skin and the pressure bulkhead.  Structural checks, carried out at the time by JAL engineers, revealed no problems anywhere else (top skin, wing retaining bolts, engine pylons, etc.).
What is the next step?
Telephone Boeing.  “I’m sorry, Mr. Boeing-san, but we feel that this repair is beyond our expertise.  Please help.”
Boeing looked at the damage and produced a ‘Repair Plan’.
Got that?  A ‘Repair Plan’.  This is a normal procedure for manufacturers of all aircraft.  Your aircraft is broken and there is nothing in the Structural Repair Manual (SRM) to cover it?  Call the manufacturers and get a ‘Repair Plan’ from them.
Boeing produced the plan and sent engineers, at the request of JAL, out to do the job.

A note about engineers.  And American practices.
Thirty years ago we worked with the United States Air Forces in Europe (USAFE).  They were good and conscientious lads—and girls, too.  If they received an amendment to one of their manuals (TO—Technical Orders, they called them) they would not just insert the amendment as we did.  No, no!  They checked EVERY page in EVERY book!  Very, very time consuming and a task that would bore any living engineer or mechanic to tears.
Similarly, when they went out to do a maintenance check on an aeroplane, they would follow the book precisely:
Page 1, Paragraph 1—Check ‘item’ in left undercarriage bay.  (Tick—done.)
Page 1, Paragraph 2—Check ‘item’ in right undercarriage bay.  (Tick—done.)
Page 2, Paragraph 3—Check ‘item’ in left undercarriage bay.  (Tick—done.)
Page 2, Paragraph 4—Check ‘item’ in right undercarriage bay.  (Tick—done.)
....and so on.
We did a circular route around the aircraft rather than hop from one side to the other and back again.  But their rules said ‘follow the book’.

But we still ‘follow the book’ when it comes to what to check, when to check it and how to check it.

Back to Japan.
The engineer from Boeing has arrived in Japan with his favourite tools and gets out the ‘Repair Plan’.
He follows the ‘Repair Plan’ because he knows that if he gets creative with it there could be very nasty repercussions.  The words ‘Big Black Smoking Hole in the Ground’ spring very readily to mind at such times.
He does as he is told.  The supervisor checks ‘The Plan’ and the repair.  The Quality Assurance manager checks ‘The Plan’ and the repair.
Everything matches.  All is well.
But it wasn’t.
The person, or team, that drew up the ‘Repair Plan’ got it horribly wrong.  The Manager who approved the ‘Repair Plan’ got it horribly wrong.
And then....
The engineer, his supervisor and the QAM should have thought “Hello!  Something odd about this.”  They should have queried Headquarters.
These are experienced people.  They didn’t ask.

Never be afraid to ask.


We are so drilled into ‘following the book’ that we forget that, sometimes, it is right to ask.  Sometimes your duty is to ask.

It can save lives.