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.......

It was a couple of days ago...

I agree. The amount of fuel in the aircraft is measured in weight, but the amount of additive to be added is in volume.

The AMM writers were a bit sloppy with that procedure. I haven't checked the Airnav glossary recently, but I wonder if PPM is actually there. And in any case, how hard would it have been to clarify and write Parts Per Million?

Airbus manuals are usually full of charts and tables. Why didn't they add one detailing the amount of additive according to fuel tanks contents.

Bear in mind that at Airbus the Technical Author is unlikely to have English as their first language, as well.

So who proves reads the manuals after they are initially written, anyone close to hand, office cleaner? For heaven's sake, to say that a Tech author is unlikely to have English as their first language is ridiculous, employ one who does have English as their first language. Simples!

Quite true, French is my second language and often it helps when trying to decipher what is required by the AIB manuals.
I'll also add that many of the employees, including I suspect the ones that write the manuals have never worked in aircraft maintenance. A couple of years ago during an Airbus audit I was asked a question, my reply was "we use the SRM"
The next question was "what's an SRM?"

I think they are proof read by someone who might have a good grasp of English but not necessarily technical English.
Still, at least they are better than the Sukhoi manuals, I think they used Google Translate on those !

It was noted somewhere in the report that PPM was not in the Airnav glossary.

Who proofread that?

It is in my pdf copy of the MM. I dont now have access to Airnav so cant check that.

Airbus is kind of a large company with a very broad employee base in their engineering departments. I wouldn't even consider a shortfall in writing skills towards the benefit of their customer base. What to communicate, how and where.may be argued here.

A lot of perfect humans on here!
Passing comment is fine,but passing judgement, without being in possession of all the facts is rather dumb!

Everyone has screwed up royally in the work place,if you never have,it’s just a matter of time! To hear some of the posters pontificating on this is rather irksome.When you screwed up or when you screw up,it doesn’t necessarily make you an idiot,just human! Next you’ll all be telling me you’ve always follow procedures............

I can't check either, I don't have access to Airnav from home but it looks like it may have been revised, here's an extract from page 10 of the report."In addition, the AMM task instructions used the term ‘ppm’ for which there was no definition within the AMM glossary, and no additional guidance was provided of how to perform the biocide fuel dosing calculation."

Quite true,
The only way to never f*ck up is to do nothing !

Yes, the way I calculate additives in the winery is 1 ppm = 1 mg/L. This makes it very easy to do rough calculations on the fly and is a good check before dumping stuff in.

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?

A case of a point for the voices saying ppm is hard to grasp on the line:

• density of jet fuel 0,785
• density of Kathon 1,05

Which are the actual correct units to be used for diluting the additive according to AMM and the spec-sheet? Molecular, mass, or volume?

Are you suggesting that fuelling in cubic metres could catch on ?

Ok, call it kilo-liters if m3 sounds overly continental for the islands. 8-)

Two morals of the story:

• mg (mass) / l (volume) is perhaps fine for a winery (density 1,005 - marginal error). For jet A1 (0,785) and Kathon (1,05) mixing volumetric and mass units gives you a nice compound error 26% even if you get the multipliers right and/or avoid the trap of mis-reading a comma in-lieu of a dot for the decimal divider.
• If there's ml one side, for PPM to work instinctively i.e. avoiding the order-of-magnitude error, you need to have kilo-liters (m^3) on the other. Well pointed that's not the case, hence the argument of PPM being a stupid choice of a field-deployable unit.

Question stands. Which units - weight or volume - are used in the original Kathon recipe of the AMM?

The answer is 'volume' - I did notice though that if you are using Biobor then the units are 'weight'

https://cimg1.ibsrv.net/gimg/pprune....53c7fe880e.png

As an aside if you use a metered injection rig to carry out the addition of the Kathon, the AMM provides a handy calculation chart to get the correct amount.



https://cimg0.ibsrv.net/gimg/pprune....0e6a030d52.png