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A321 AAIB Report: Mayday/emergency landing due to fuel additive error

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A321 AAIB Report: Mayday/emergency landing due to fuel additive error

Old 27th Apr 2020, 21:11
  #81 (permalink)  

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'volume' - I did notice though that if you are using Biobor then the units are 'weight
Priceless.

Thanks. The page from your second post instructs to use KG reading in order to add biocide PPMs by volume. Right, no further questions.

Last edited by FlightDetent; 27th Apr 2020 at 21:21.
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Old 27th Apr 2020, 21:14
  #82 (permalink)  
 
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Originally Posted by FlightDetent View Post
While I can attest that operating a contemporary jet is not an exact science, certainly there is hope that the engineering would be. PPM stands for 1 x 10^(-6), no units given - it's a simple multiplier. That does not taste right. Perhaps mg/kg or ml/m^3, anyone?
When adding weight per volume, which is how this additive is used, it's exactly right. For example, if the rate of addition (I'm just making up numbers here} is 100 ppm (100 mg/L) and the volume of fuel is 7000L we would need to add (100 mg/L)(7000 L)/1000 mg/g = 700 g or .7 kg. Pretty simple.
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Old 27th Apr 2020, 22:46
  #83 (permalink)  

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Not sure altogether if we are speaking about the wine or biocide. Wine has a density of 1,005 so mixing weight (mg) with volume (l) is a foul play that gives acceptable results.

Hopefully, we agree that ppm is a unit-less multiplier. Per-cent is 1/100, per-million is 1/10^6.

The AMM above says PPM (by volume) thus I would expect a proper calculation in volume : volume units. To adress the density issue (fuel tank gauges in KG, dosage in l or ml - I only assume here), the calculation guidelines in a pilot-proof world would need to take this form:



Using your numbers of 7000 L fuel to achieve 100 ppm by volume, 0.7 L of agent needs to be added. And that is 735 g of the matter. If you say the recipe on the can does actually instruct to mix mili- or kilo- grammes on one side and mili- or full liters on the other (either way) - I'll take your word for it. But calling that ppm is gobbledygook.

One more thing I inserted into that pilot-proof example. Realistic values. Which provides the reader with an outlook on what his result should look like. Compare that with the AMM original text suggesting adding 10000 kg / lbs ontop 10000 kg/lbs of fuel already there. Pardon me? There is no tank on the machine that'd hold 10.000 kg of fuel nor 20000 lbs by a wide margin!

Massive case study on how many things can be unhelpful in a technical writing. Unhelpful actually does mean incorrect and wrong. Human Factors - biting the bottoms since well before the Wright brothers.

With Occam's razor, my gut feeling is that the decimal denominator "," "." actually got mixed (same happened in posts #56 and #57 here) and something got multiplied by 1000 rather than divided. Who knows, happy everyone survived to tell the tale.

Last edited by FlightDetent; 27th Apr 2020 at 23:08.
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Old 28th Apr 2020, 00:57
  #84 (permalink)  
 
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I agree with you. My confusion, as I am not in aviation, was with the (for obvious reasons) aircraft usage of weight of fuel versus volume. I was calculating weight/volume for the ppm addition as the amount was reported in kg.
Using your numbers of 7000 L fuel to achieve 100 ppm by volume....
I understand. Anyway, this stuff is so simple and it's so easy to generate a simple spreadsheet or graph to do it automatically........ Kg fuel in, addition rate calculated.
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Old 28th Apr 2020, 01:38
  #85 (permalink)  
 
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Originally Posted by Big Pistons Forever View Post
Nobody has talked about the role of the regulator here. The engineer held a license issued by an aviation authority with skills and knowledge requirements defined by them, arguably significantly dumbed down from what used to be required. The manual he was using and which you could make an argument was not fit for purpose, was approved by the authority.

industry on both sides of the Atlantic have actively pushed to marginalize and neuter regulators. This works great and saves manufacturers and air operators tons of money until the airliner dives itself into the ground or the whole rotor comes off the transport category helicopter at 2000 ft AGL.......
I wish there was a "Like" button sometimes.

Your post summarises it.
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Old 28th Apr 2020, 06:40
  #86 (permalink)  
 
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Originally Posted by FlightDetent View Post
The AMM above says PPM (by volume) thus I would expect a proper calculation in volume : volume units. To address the density issue (fuel tank gauges in KG, dosage in l or ml - I only assume here), the calculation guidelines in a pilot-proof world would need to take this form
The fly in the ointment is that, as the report makes clear, Kathon FP1.5 is packaged and supplied by weight, not volume:


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Old 28th Apr 2020, 08:03
  #87 (permalink)  
 
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Make the adding of any additives to fuel a duplicate inspection item . Surely they cant have 2 people working for the same organization capable of making such a monumental mistake ?

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Old 28th Apr 2020, 09:23
  #88 (permalink)  

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Originally Posted by DaveReidUK View Post
The fly in the ointment is that, as the report makes clear, Kathon FP1.5 is packaged and supplied by weight, not volume:
That's logistics, how you administer it is what matters. Pouring it out of the canister into a measuring cup, what are the gauges on it? A volume-labelled cup is easy to find, calibrate and fits the calculation of PPM (by volume) easier. A mass-calibrated cup is imaginable, as well as a dosing device that weights the substrate.

Neither is of which is my expertise and admittedly in line with your remark the AAIB Bulletin (thanks for making me actually read it) has an extra step. To convert the volumetric dose figured through the ppm (by volume) requirement into mass for Kathon.

My aim was only to illustrate how much different the form of the instructions for mixing needs to be compared to the unusable excerpt we've seen from of the AMM. Well, if that were meant for pilots to read and apply.

Given the past performance of the authors, I will be excited to read the full report later. Neither my equation nor the calculation in the bulletin addresses the practicality for ramp use. In that respect both are equivalently not too good, requiring several steps to derive the input values first. Let's see how many loose ends they will find.
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Old 28th Apr 2020, 09:56
  #89 (permalink)  
 
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Competent engineers should be expected to be able to work accurately with either.
You're absolutely right, it's not a complicated calculation. But it *is* easy to get wrong with very little indication that you've made a mistake.

Someone who's sat comfortably at a desk, during the day, with no time pressure is able to complete this calculation repeatedly and without difficulty. At 3am, cold, hungry and covered with JET A1 is a totally different proposition.

At this point there's not necessarily a huge point in making someone else repeat the calculation independently, because two people can get it wrong. Putting a big label on the can that says "this treats approximately 50 tonnes of fuel" is a bit of mental maffs that anyone can do.
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Old 1st May 2020, 08:18
  #90 (permalink)  
 
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Originally Posted by Fursty Ferret View Post
Putting a big label on the can that says "this treats approximately 50 tonnes of fuel" is a bit of mental maffs that anyone can do.
There's the answer, right there to this "Swiss cheese line-up".

The only thing I would add is, have a clear pictogram of that information on the container as well as text* The poor sod covered with JetA1 at 03:00 might not speak or read English very well..............

*Or even better maybe: a series of marks down the container side with a clear band to see the liquid level through, and the amount of JetA1 that fluid up to each mark would treat.
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Old 1st May 2020, 10:53
  #91 (permalink)  
 
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Originally Posted by stormin norman View Post
Make the adding of any additives to fuel a duplicate inspection item . Surely they cant have 2 people working for the same organization capable of making such a monumental mistake ?
You make good point. You are, after all, working on both engines at the same time on an ETOPS capable aircraft.
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Old 1st May 2020, 14:15
  #92 (permalink)  
 
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Lot of current production aircraft have no overwing refuel capability. Therefore an alternative procedure to put baobar in is required. As its not generally specified in the AMM of a lot of types it should be a company procedure as per their 145 approval to specify what equipment and how . Probably in the to difficult pile for the auditors from all the different authorities that most MRO's hold approvals from as we're in an environment of approved companies now so not just an individual .
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Old 1st May 2020, 14:42
  #93 (permalink)  
 
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Originally Posted by bvcu View Post
Lot of current production aircraft have no overwing refuel capability. Therefore an alternative procedure to put baobar in is required. As its not generally specified in the AMM of a lot of types it should be a company procedure as per their 145 approval to specify what equipment and how . Probably in the to difficult pile for the auditors from all the different authorities that most MRO's hold approvals from as we're in an environment of approved companies now so not just an individual .

The equipment to use to inject Biobor is specified in the MM

COM-1781 HAND CART STYLE ADDITIVE INJECTION SYSTEM
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Old 4th May 2020, 07:45
  #94 (permalink)  
 
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Originally Posted by TheReverend View Post
And the press interpreted "A "stall" message was displayed in the cockpit three times" to mean the second engine stalled. I'm assuming the stall warnings were due to low-airspeed and high AOA.
Surely “three times” must mean that engine #3 failed as well?

/tabloid mode
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Old 11th May 2020, 09:27
  #95 (permalink)  
 
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Fursty Ferret;

As a former (miltary) engineer and latterly ICU Nurse Specialist, I can testify that proportional calculations can be problematic. Millilitres per litre and micrograms per kilo body weight etc can prove head wrecked when under stress. The PPM issue though is hard to credit......
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Old 12th May 2020, 06:58
  #96 (permalink)  
 
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The data sheet,
Aviation Fuels - Water and sludge should be removed from fuel tanks before application of the biocide.

100ppm v/v of KATHON™ FP 1.5 as supplied should be used to achieve microbial control, as described by EU BPD and US EPA regulations. To achieve this, the user should treat every 10,000 litres of aviation fuel with 1 litre of KATHON FP 1.5. The biocide should be added in such a manner so as to allow good mixing and distribution across the fuel. Ideally, this should be into a fuel supply line to ensure agitation. A contact time of up to 24 hours is recommended, depending on the severity of infection.
I presume your fuel is dispensed in litres, so a simple calculation to make if abiding by the data sheet. Seems Airbus may have overthought the procedure.

http://msdssearch.dow.com/PublishedL...romPage=GetDoc

Looks like Kathon is being replaced with FuelClear AV15 - awaiting aviation approval. The company says "Kathon FP 1.5 Fuel Biocide is being discontinued for aviation applications with immediate effect". Result of this incident?

https://www.fuelcare.com/industries/...lear-av15.html

Am I missing something? The Airbus manual talks about mixing by volume then uses weights for the calculation. One doesn't equal the other, specific gravity of the product is 1.04.

Last edited by megan; 12th May 2020 at 07:22.
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Old 12th May 2020, 07:59
  #97 (permalink)  
 
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Don't forget the Airbus restrictions are based on the biocide causing problems with the aircraft, while the manufacturer's instructions have the goal of killing anything unwanted in the fuel. They might not be comparable.
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Old 12th May 2020, 08:32
  #98 (permalink)  

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Am I missing something?
The AMM is completely messed up. Even if you manage to follow that guidance, you'd reach an incorrect result.

Although for the accident in question mistakes had been made between the AMM and the bowser, an order of magnitude greater.
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