ROMA MARIO (IT)
ROMA MARIO (IT)
| 1. | Claim 1: To force the natural nebulization of hydrocarbons in the ullage in order to create a very weak pressure with respect to the surrounding environment, and such as to never allow entry of external air through air vents installed in the tanks (also through heating). Perhaps in the past and also today, it is paradoxical that the accidental overheating of wornout electric systems or improper functioning of pumps should have produced 'heat' in the ullage, thereby increasing relative pressure, and consequently constituted elements of safety. Claim 2: The use of Italian patent n° 01300359 is suitable to solve the ullage question and/or may serve as a substitute for the previous solution. It should be noted that the latter solution (Italian patent n° 01300359) differs from the former as it improves safety in oxygenated environments where, in any case, it is necessary to ensure the survival of vulnerable personnel as in the case of mines, hyperbaric chambers, bunkers, armoured military vehicles (tanks) and aircraft fuselages and cabins etc. Claim 3: Besides causing fuel pollution, the addition of additives (e.g., halon, nitrogen etc) to the ullage can generate nitrate compounds (explosives), which, although not dangerous (on account of high dilution) may nevertheless contribute at high temperatures towards the corrosion of turbine blades. Claim 4: In consideration of the various consequences and conclusions that may be drawn from a full comprehension of this report, it was deemed appropriate that the same be brought to the attention of the judicial authorities. By means of both physical and mechanical means, and by a monitoring and selection of fuel tanks, and with a reduction in hourly consumption rates, it is possible on all occasions, and in all circumstances, to attain a greater degree of protection against the risk of fire in aircraft fuel tanks. From the technical point of view, such a higher level of safety is obtained by 'forcing' and controlling the natural, spontaneous evaporation of fuel in the empty parts of tanks (ullage) at a pressure, which, under all flight conditions, should be slightly higher then the external pressure. In such manner, it is moreover possible to ensure the invulnerability of fuel tanks with respect to free, internal / external flames. |
Description
1. The present finding regards fuel tanks mounted in aeroplanes, rendered fireproof by means of technology already present and applied in terrestrial and surface transportation vehicles such as ships, automobiles, trucks, coaches, etc.
Management of ullage
2. The question of safety in flight is a field which requires the continuous attention of everyone and is supported by the very best that technology has to offer. The following discussion serves to illustrate proposals for improvement (claims), which can be applied to aircraft, some of which are moreover in sharp contrast with current solutions [cf. ref. (f), pg. 18].
In my modest opinion, such conclusions may be important for all persons directly or indirectly involved with aircraft. Moreover, in order to illustrate the proposals mentioned above, I shall briefly discuss currently adopted fuel- handling techniques by way of a premise.
3. In the handling of hydrocarbon fuel, proven technology currently provides for a sufficient degree of safety throughout the entire fuel production chain, from drilling and extraction of oil deposits to the filling of automobile petrol tanks. Normally, liquid hydrocarbon fuels are contained in tanks, in which there is an internal, unfilled space (ullage) above the fuel. This space is occupied by gases emitted by the fuel itself.
The ullage comes into contact with the environment outside the tank by means of bi-directional vents, which, in terrestrial vehicles, are in fact uni-directional as they continuously emit constantly-forming vapours. This system is the most secure of all. In fact in the ullage space (n.b. while other openings are closed) it is even possible to use free flames.
4. However, during certain operations, such as the emptying of petrol-tankers, certain anomalies may arise:
If not promptly followed by corresponding vaporization inside the ullage, rapid removal of fuel creates a vacuum inside the ullage space and thus a dangerous intake of air from the outside of the tank or through the vents.
This problem has been solved in quite a casual manner in petrol tankers by introducing into the tanks a quantity of sea water, which has other beneficial effects which I shall not mention here. On the basis of the above, it can be clearly understood that this successfully employed technique is more important as a form of prevention than in attempts to limit damage occurring after accidents.
With regard to fuel:
- a relatively low hourly fuel consumption rate in land vehicles;
- low outflow of fuel; and
- continuous movement (starting and braking),
create elements of risk, as previously mentioned.
5. From the publication referred to in the document 'Edit 2003 ' [cf. ref.(f)] it can be seen that the solution illustrated in the previous paragraphs has not been applied to aircraft in a complete form, and no controlled forcing of natural nebulization yet exists (claim), such lack being the cause of a degree of vulnerability with respect to open flames under certain conditions, i.e, :
- strong hourly consumption of fuel (as aircraft gains altitude);
- the absence of the movement of fuel inside tanks;
- considerable lowering of pressure and temperatures (at high altitude);
- condensation of vapours always possible.
Such conditions may combine and as a result generate a vacuum in the ullage space and thus a dangerous intake of external air through installed vents.
6. In the accident-review literature [cf. ref (f)] 5 the points illustrated above have never been taken into consideration, thereby inducing post-accident analysts to consider hypotheses which involve such 'common-knowledge' causes as:
- faulty electric cabling [ref (a), pg. 114];
- transfer pumps [ref (a), pg. 114];
- hijacking [ref (a), pg. 49]; and,
- lightning bolts.
7. Security can be improved by adopting, as an alternative and/or auxiliary measure, the concepts indicated in the Italian patent [cf. ref. (h)] (claims), i.e.,
- forced controlled nebulization of fuel in the ullage space;
- supplying aircraft with pre-heated and de-gased fuel [cf. ref. (h); i.e., patent n° 1300359], as opposed to the concepts contained in the text referred to herein as
'Edit 2003 ' [ref (f), pg. 118, line 13]), which also facilitates the de-icing of wings;
- decreasing the rate of climb (reduction of hourly consumption);
- monitoring ullage pressure;
- the selection of other tanks wherever possible; and, thus achieving a degree of security which can be referred to as the 'free flames' condition.
Other solutions, such as an ad-hoc use of pollutant, chemical additives can worsen the problem as such substances pollute the fuel itself [cf. ref (f) pg. 117, line 24, and pg. 273].
8. Ideally, the above can be added to our conclusions [cf. ref (f), pg.295]. Moreover, anyone wishing to undertake in-depth studies of this issue - before engaging in debate regarding such matters (and/or prior to their next flight) - is invited - and would be well-advised - to consult the following documents:
- ref (f) ( 'Edit 2003 ') (the full title of this document is contained in a report submitted to the Italian Police (Carabinieri) at Brendola, in the province of Vicenza, on 15th March, 2004 at 16.45 hrs); and also,
- ref (g) (diskette entitled 'Oxy') (submitted to the Italian Police (Carabinieri) at Brendola, in the province of Vicenza on 18* 0^, 2004 at 11.50 hrs) (as was the present document).
Before reflecting upon the next point, the texts referred to above must be clearly understood.
9. Management of ullage
Careful study of the previous section (1) will reveal that :
- The question of ullage safety is common to all aeroplanes and some aircraft manufacturers have become aware of the problem [cf. ref. (a) and (b)]; - T'he problem has not yet been solved in a valid manner [cf. ref. (d)];
Some aircraft designers [cf. ref. (f)], pilots, purchasers of aircraft, flight staff, and, generally, all passengers worldwide are deemed to be unaware of the ullage question;
The previously suggested solution (Italian patent application VI 20048261 dated 11.11.2004) is once again proposed here:
References
a) http://www.easa.eu.int/home/consultation_crd_en.html Source: Comment / Response Document CRD 2005-006 for Special Condition No. RP-747-E-01 for Boeing Model 747 Series. "Aeroplanes Flammability Reduction System (Fuel Tank Inserting)." Date: 19.08.2005 (36 pages); and,
Source: Special Condition No. RP-747-E-01 for Boeing Model 747 Series. "Aeroplanes Flammability Reduction System (Fuel Tank Inserting)." Date: 19.08.2005 (16 pages);
b) http://www.swsciences.com/research/papers
Source: "Detection of Explosive Mixtures in the Ullage of Aircraft Fuel Tanks" S. J. Chen and J. A. Silver, Date: 09.01.2004 (10 pages);
c) http://www.aviationnow.com/ Journal: "Overhaul and Maintenance" (issue: December 2004) Safety Regulation News (pages 17, 18 and 19);
ά) Article: "Manufacturers Question Fuel Tank System Part 25 Changes" by Sean Broderick:
e) Patent application VI 2004A861 dated 11.11.2004; transcribed in full herein as an integral part of this document (cfr. Pars. 2 - 9 incl.);
f) Edit 2003;
g) Diskette 'Oxy' dated 18 th Oct 2004 11 :50 hrs.;
h) Patent n° 01300359.
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