Abstract:
A washing unit for turboprops of aircraft comprising a hydropneumatic accumulator suitable for supplying washing liquid contained therein at a controlled pressure, and a filling member, motorized and manual, for feeding the washing liquid into the accumulator, which can be connected alternatively to the motorized filling member or to the manual filling member. A manually actuated device is also provided for pressurization of the accumulator, so that the washing unit can be used both in areas equipped for this operation and in non-equipped areas.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a portable and modular washing unit for turboprops of aircraft, more particularly P&amp;W PT6T Series T3-T6 turboprops, installed on the helicopter AB 412, and Lycoming LTP 101-700, installed on the Piaggio P166 DL 3SEM aircraft, or equivalent. 
       BACKGROUND ART 
       [0002]    The problem related to the gradual accumulation of saline residues and contaminants dispersed in the air on the surfaces of the blading and of the rotor of the turboprops of aircraft is known. This phenomenon progressively impairs the functional parameters of the turboprop that must therefore be restored in order to avoid jeopardising the efficiency of the machine. The traditional devices for cleaning compressors are heavy and bulky and totally unsuitable for transport on an aircraft such as a helicopter, or for use in field during working missions. 
       SUMMARY OF THE INVENTION 
       [0003]    The object of the present invention is to provide a washing unit for turboprops of aircraft that is easy to transport and to use both for desalinating washes and for performance restoring washes and which allows the maximum practicality, maneuverability and transportability during operations of washing and performance restoring of the aircraft turbines, both in conditions of operation on the runway and in areas lacking in any energy source. 
         [0004]    This object is achieved with the portable and modular washing unit for turboprops of aircraft according to the present invention whose basic features are claimed in claim  1 . 
         [0005]    The features of modularity, compactness, lightness, simplicity and possible air transport make the washing unit according to the present invention the ideal instrument for routine maintenance, which can be performed on the aircraft, both in areas devoted to the aircraft maintenance or outside in emergency areas. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The features and the advantages of the portable and modular washing unit for turboprops of aircraft according to the present invention will be made clearer by the following description of one of its embodiments, given by way of a non-limiting example with reference to the accompanying drawings, in which: 
           [0007]      FIGS. 1 ,  2  and  3  show the washing unit according to the invention in a front, side and rear view respectively; 
           [0008]      FIGS. 4 and 5  are front and rear perspective views of the washing unit of  FIG. 1 ; 
           [0009]      FIG. 6  is a plan view of the control panel of the washing unit according to the invention; 
           [0010]      FIG. 7  is a plan view from the inside of the control panel of  FIG. 6 , specularly reversed in relation to the latter; 
           [0011]      FIG. 8  schematically shows the hydraulic circuit of the washing unit according to the invention; 
           [0012]      FIG. 9  shows in a front view two washing units according to the invention, connected modularly one to the other; 
           [0013]      FIG. 10  shows a set of accessories associated with the washing unit according to the invention that can be adopted for use in non-equipped areas. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to  FIGS. 1-5 , the washing unit according to the invention comprises a frame  1  with open welded and box-shaped profile, mounted on wheels  2  to ensure easy towability thereof and fitted, on the upper side, with a pair of tiltable hand-grips  3  for its towing or pushing and three pairs of handles  4  for its raising. A pair of the handles  4  extends from a control panel  5  located at the top of the box-shaped frame  1 , while the other two pairs of handles  4  extend at the sides of a front panel  6 , on which the connection is provided for manual filling means, as will be described herein below. On a rear panel  7  there are hydraulic connections for service fluids and, again at the rear, a further panel  7   a  is provided on which the electrical connections to the aircraft and a pressure gauge  35  indicating the pre-charge value of the accumulator are present. 
         [0015]    As shown in particular in  FIGS. 4 and 5 , an electrical pump  8  is placed on the base of the box-shaped frame  1  and a hydropneumatic accumulator  9  is placed above the pump  8 . The accumulator is a stainless steel tank divided into two chambers by a separation membrane  10 , as shown in the hydraulic diagram of  FIG. 8 . The two chambers of the accumulator  9 , denoted by  9   a  and  9   b  in  FIG. 8 , are intended to contain respectively a washing fluid and a pressurisation fluid, in particular compressed air. The feeding of washing fluid into the chamber  9   a  of the accumulator  9  causes an increase in pressure of the pressurisation fluid present in the chamber  9   b  up to a predefined value. The pressure that is generated in this way in the accumulator  9  provides the necessary energy for the washing fluid supply. The value of the final filling pressure is considerably higher than the pressure of use, so that at the output of the chamber  9   a  a pressure regulator  11  is provided ( FIGS. 7 and 8 ), installed on the delivery line  12  of the accumulator  9 , which reduces the pressure of the washing mixture to the value-laid down by the washing specifications established by the manufacturer of the turboprop, allowing a controlled outflow of the mixture. The delivery conduit  12  is connected to the accumulator  9  via a three-way valve  13  and a pipe  14 . 
         [0016]    The electrical filling pump  8  sucks the washing fluid from a tank  15  and is connected to the three-way valve  13  via filling conduits  16  and  36 . The chamber  9   b  can instead be connected via a hose  17  to pressurisation means, for example a battery compressed air gun or a pedal pump. 
         [0017]    The washing module also has two connectors  18 , respectively on the filling conduit  36  and on the hose  17 , for the hydraulic connection to portable filling means for the washing and pressurisation fluid that can be used when washing operations have to be performed on field during a working mission in areas where suitable equipment or electrical energy are not available. More particularly, these portable means comprise a manual pump  21  and a pneumatic pedal pump  20  for feeding the pressurisation fluid into the chamber  9   b  of the accumulator. Alternatively the manual pump  21  can be replaced by the electrical pump  8 , which can be connected to the service intake of the aircraft, like the one shown in  FIG. 4 . Other useful accessories, which may be contained conveniently in a special bag  22 , can be a flexible tube  23 , used for the delivery of the washing fluid, and a set of accessories for attachment and depressurisation  24 . 
         [0018]    As shown in  FIGS. 6 and 7 , positioned on the control panel  5  are a pressure gauge  25  for the control of the delivery pressure, a pressure gauge  26  for the control of the level of fluid available inside the accumulator, a key  27  for the opening and closure of a delivery valve  28  located on the delivery conduit  12  and a key  29  for setting the three-way valve  13  from the working position to the filling position and vice versa. The valves are positioned immediately below the control panel  5  as shown in  FIG. 7 , where the valve  11  for regulating the supply pressure of the washing liquid is also shown. 
         [0019]    The washing unit according to the invention also provides for the possibility of blowing nitrogen during washes performed on particular turboprops (for example the Lycoming turboprop installed on the Piaggio P166 DL3 aircraft). For this purpose a bypass  30  is provided, with relative fast couplings mounted on the panel  7  for the connection to a feed hose (not shown) coming from the gas cylinder and a supply hose (not shown), as well as a feed valve  31  and a control pressure gauge  32  placed respectively below and above the control panel  5 . 
         [0020]    The washing unit according to the present invention allows the performance both of a desalinated washing of a turboprop, performed with distilled water, and the washing for the recovery of performances which, as is known, is carried out in two steps. During the first step a mixture of distilled water and detergent is used, while in the second step a double rinsing with distilled water is carried out. 
         [0021]    Thanks to the accessories supplied, the washing unit according to the invention can be transported on the aircraft in a totally emptied and depressurised condition, for example in the tail boom of a helicopter, appropriately attached via the various anchorage points formed on the frame  1 , during a mission to use it in non-equipped areas. 
         [0022]    Moreover, given its total modularity, two washing unit modules according to the invention can be joined together, side by side, as shown in  FIG. 9 , for use in a hangar, in the case of washing to restore performances wherein a mixture of detergent and distilled water for the subsequent rinsing has to be used. 
         [0023]    Variations and/or changes may be made to the washing unit for turboprops of aircraft according to the present invention, without thereby departing from the scope of the invention as set forth in the following claims.