BACKGROUND-STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH Not Applicable.

BACKGROUND-FIELD OF INVENTION This invention relates to aircraft safety improvements, spe- cifically an efficient, economical method of using an aircraft's propulsion or auxiliary power unit engine or air-handling blower unit or off-board air-handling air-conditioning apparatus for new purposes of purging and removing dangerous and explosive fuel tank fume-vapors including purging and removing heat surrounding a fuel tank and circulation of air in unoccupied smoke-alarmed areas to speed, up warning response time.

BACKGROUND-DESCRIPTION OF PRIOR ART . Past. and.. p'Ee sent day engineering design in. commercial and corporate-business aircraft to remove explosion potential in fuel tanks has been to design out all energy sources which could ignite the explosive fumes there-iw. he histoxy of aircraft fuel-tank explosions and especially the tragic results of the recent T. W. A.

Flight. 800 explosion and crash show that designing out all possible energy sources is impossible.. Furthermore, even if it were possible to remove all on-board energy sources it mrould be impossible to re- move'external energy sources such as bullets,, missiles, meteors and lightning strikes. Some solutions other than-designing out energy sources have been proposed. One current proposal is tco purge fuel <BR> <BR> tank ullage areas of dangerous explosive fume vapors and to remove<BR> <BR> <BR> <BR> <BR> <BR> heat. from areas surrounding fuel tanks'which promotes vaporization by introducing ram air into and around the fuel tank.. Problems-, as"- emaciated with. ram air. methods'are creation-of drag,. introducing un'.- burned fuel fmnes into the atmosphere and most importax 5. ram air methods require, motion to work and wd. 11 therefor not operate at a most. critical time when aircraft build. up heat and vapor'while on the tarmac or'runway waiting for take-off clearance.. Another pro.-' posal. is t. reduce the fuel tank ullage area and. consequently the fume-vapor build-up by always carrying a minimum amount of fuel in the tank. Problems associated with this method are continual weight penalties, operational constraints and inability to always maintain the minimum :, amount, of. fuel in the tank. Another propos'al was'to cool fuel tanks by using colder fuel again, problems with this me- thod is operational constraint and inability to maintain fuel temp- erature after fueling-... Past and present day military solutions for the prevention of'fuel tank explosions is to introduce inerting gas- into the fuel tank ullage area so that dangerous fume-vapors will not. accumulate there-in. The well known drawbacks to these systems are weight penalties and maintenance nightmares including the high cost and complexity of these systems. Historically the operation of these systems have created some safety problems of there own. Also, the displaced unburned hydrocarbons caused by these methods create <BR> <BR> <BR> atmospheric pollution... A current fuel tank inerting method proposes utilization of engine exhaust as an inerting gas. Problem assoc- sated with this method od include the cost and weight of the system needed to treat and introduce exhaust gases to the fuel tank and the inherent corrosiveness of the exhaust products. In regard to smoke alarm speed up aspect of this invention, present day aircraft alarms rely on activation by gravity or passive circulation of contaminated air however,, many times valuable time is lost. before contamination. products reach the detector by these passive methods. Of course, de- tector-alarms are useless if contaminants do not reach and activate them. With these passive methods of circulation, fires can smoulder <BR> <BR> <BR> for long periods of time before smoke and/or fire products'reach the detector and alarm delays can cause greater death, injury and damage.

SUMMARY In accordance with the present invention, temperature controlled, pressurized circulating air is provided by the aircraft's dedicated propulsive or auxiliary power unit engines or comfort air air-hand- ling blower or off-board air-handling air-conditioning apparatus, preferably through the aircraft's occupied cockpit-flighdeck-cabin outflow air mechanism to purge and remove dangerous and explosive fuel tan tank fume-vapors from within the fuel tank and fume-vapor caus- ing heat from around the fuel tank while also circulating air in the aircraft's unoccupied smoke-alarmed areas to speed up smoke alarm detector response with resulting fumes, heat and air being vented to the aircraft's engine outside air low pressure intake suction or to the atmospheric ambient air.

OB= : S AND ADVANTAGES Accordingly, the following objects and advantages of the present invention are: (a) a) to provide the simplest and most efficient, economical, safest, reliable method, for removal of aircraft fuel tank fume-vapors and heat to reduce explosive and flammability potential and to speed up smoke alarm response time; (b) to provide a method to reduce an aircraft's fuel tank ex- plosive potential and reduce smoke detection alarm time that can be easily and. inexpensively retrofitted to existing aircraft systems; t. a provide a method for the reduction of fuel tank explos- i. on and. increase of smoke alarm response time that does not require aircraft motion; (d) to provide a method for the reduction of fuel tank explos- ion and increase of smoke alarm response time that does not require an. aircraft to power up; (e) to utilize cockpit-flightdeck-cabin waste outflow air for the reduction of explosion potential and increase of smoke alarm response time; (f) to combust unburned hydrocarbons that were previously vented to the atmosphere; (g) to increase the aircraft's engine efficiency by enriching engine s.'o. m'buation- intake air with. fuel fume-vapors' (h) to. replace fuel tank fume-vapors with a lower oxygen, higher carbon-dioxide content cockpit-flightdeck-cabin outflow air; (i) to replace fuel tank fumes and fuel tank compartment heat by cooler mechanically conditioned or cockpit-flightdeck-cabin outflow air ; that that an off-board air-conditioning unit be used as a combi nation. air-conditioner and fuel fume-heat remover and smoke-alarm sir circulating unit ;' (k) that an off-board air-conditioning unit be used for a new purpose of fuel fume-heat remover and smoke-alarm air circulating unit; at !.) that an aircraft's dedicated propulsive engine be used as a combination propulsive engine and fuel fume-'heat remover and smoke-alarm air circulating unit; (m) that an aircraft's dedicated propulsive engine be used for a new purpose of fuel fume-heat remover and smoke-alarm air circu- lating unit; (n) that an aircraft's dedicated auxiliary power unit engine be used as a combination auxiliary power unit engine and fuel fume- heat remover and smoke-alarm air circulating unit; (o.) c) that an aircraft's dedicated auxiliary power unit engine be used for a new purpose of auxiliary power unit engine and fuel fame-heat me-heat remover and smoke-alarm air circulating unit; (p) to use this method of fuel tank inerting in conjunction with ith existing or future methods of fuel tank inerting.

DRAWING FIGURES Figure 1 is a cut-a-way drawing of an aircraft showing com- ponent parts for the purging and removal of fuel fume-vapors from the fuel. tank.

Figure 2 is a cut-a-way drawing of an-aircraft. showing-corn- ponent parts for the purging and removal'of heat from around the fuel tank in. the fuel tank compartment which is also representative of unoccupied smoke-alarmed areas for circulation of air to speed up smoke alarm response..

Detailed Descripti. on Cf The Drawings Referring. now to Figure 1 a conduit 1 connects fuel tank ul- lage area 2. to outside air intake areas of the aircraft's propul- sive engine 3 and/or auxiliary power engine 4. The duct contains one-way airflow valves including spark/flame arrestor means 5 to prevent the possibility of any spark or. flame from engines to the'. fuel tank.. With engines running and opening activation of the servo-mechanism controlled valve 6 by manual,, automatic (includ- ing thermostatic) controls', the fumes are suctioned and removed from the fuel tank ullage area. Fuel tank fumes are either exhau- sted directly to the atmosphere 7 or suctioned into the engine 7' for combustion purposes with resulting exhaust 8 into the aimons phere.. Fuel tank ullage area is replaced with off-'board, air hand- ling air-conditioning conditioned or unconditioned outside sir'di- rectly or via cockpit-flightdeck-cabin, aircraft's mechanically con- ditioned air, cockpit-flightdeck-cabin conditioned or unconditioned <BR> <BR> <BR> <BR> outflow air or outside atmospheric'ambient air 9 through fuel tank ullage inflow valve 10.

Referring mow to Figure 2 s conduit 1 connects area-surrounding fuel tank or unoccupied smoke-alarmed areas 2 to outside air intake areas of the aircraft's propulsive engine 3 and/or auxiliary power engine 4. The duct contains one-May air flow valves including spark/ flame, arrestor means 5 to prevent the possibility of any spark or flame from. engines to the fuel tank compartment area. With engine operating and o-pening activation. of the'servo-mechanism ! controlled valve 6 by manual, automatic (including thermostatic) controls, the hotter air is removed from area around the fuel tank and/or aircraft unoccupied smoke-alarmed stagnant air areas 7. Hot or stagnant air is either directly exhausted to the atmosphere 8 or suctioned into the the engine's law pressure outside, air intake 8'as-combustion or by- pass air'outflow.. The area surrounding the fuel tank and/or unoccu- pied smoke-alarmed areas is then replaced by off-board air-handling air r conditoning conditioned or unconditioned air (directly or via cockpit-flightdeck-cabin), aircraft's mechanically conditioned air, cockpit-flightdeck-cabin conditioned or unconditioned outflow air or outside atmospheric ambient air 9 through fuel tank/smolte-alarmed areas inflow valve 10. Fuel tank 11 is shown for approximate loca- tion (see Figure 1).

CONCLUSION, RAMIFICATIONS AND SCOPE Other ramifications, scope and enlightenment can be found in the Patent Application, Provisional Patent Application and Disclosure Document referenced in this application.

It should be obvious that the method is a simple, reliable and economical way to reduce the catastrophic potential of fuel tank ex- plosion and to speed up smoke alarm warning time. It should also be observed that this method can easily be incorporated in new manufac- ture of aircraft and that it readily lends itself to modification and retrofitting of existing systems and can also be used in conjunc- tion with other systems of aircraft fuel tank inertion.

An important aspect of this invention is to use the aircraft's dedicated propulsive and/or auxiliary power engine i combination form for new purposes of fuel tank fume-heat purging and unoccupied area ai circulation for faster smoke alarm response time because it obviates the cost and weight penalties of using a separate motor for these purposes- In a preferred embodiment-operation of the invention, while the aircraft is on the tarmac and before engine start-up, an off- board air conditioning unit can be used to provide the circulation air for fume-heat removal and smoke alarm sampling. The circulating air would be directed through the cockpit-flightdeck-cabin occupied areas of the aircraft first just the same as when system is used with engine operation for the added advantages of using the same apparatus (ducting, etc.) and using air that is partially inerted (breathed air has a higher carbon dioxide ratio than outside air).

After on-board engine(s) are started they can provide the required air circulation per the invention's methods and the off-board unit m be disconnected.

Two secondary but important results of this invention are the efficiency improvements of the engine due to suctioning fuel-fume enriched d air for combustion and the reduction of unburned hydro- carbons into the atmosphere. should be noted that the low pressure suctioning effect at the. aircraft's outside air intake is only used as the driving force when outside ambient air is used as the circulating air. In all other cases of operation, including the off-board source, the cir- culating purge-movement air is pressurized and can be vented to the engine outside de air intake or to atmospheric ambient air.

It sllould be abviou. s that the use of cockpit-flightdeck-cabin outflow waste air, whet er from off-board-or on-board sources, does ; mot involve added energy requirements.

This method can be used quite naturally, that is, when air- <BR> <BR> craft's-me-chanisally induc. ed cqckpit-flightdeck-eabin air is nor- mally exchanged during flight cycle operations, it uses the waste dumped air to purge and remove the fumes and heat and to circulate air in the unoccupied smoke--alarmed areas.

While one ocf the main objectives of this invention is to pre-. vent fuel tank. nk explosions during the flight cycle (tarmac to tarmac), it also serves to prevent fuel tank explosions during crash and post- crash situations.