RAIN REPELLENT SYSTEM - DESCRIPTION AND OPERATION
EFFECTIVITY
All airplanes with active rain repellent systems
1. General
A. A rain repellent system is provided to be used in conjunction with the windshield wiper system to improve windshield visibility through the pilots' No. 1 windshields during heavy rain. The system is controlled independently for each window by separate control switches located on the overhead panel and when actuated the system sprays a rain repellent solution on the respective window as selected. The maximum quantity of solution sprayed per system actuation (approx. 6cc) is predetermined by the setting on a time delay relay and cannot be exceeded by extended duration of switch actuation. The solution is spread over almost all of the window by the rain and airstream, however spreading is enhanced within the wiped area of the windows by the action of the wiper blades. The length of time that an application remains effective varies inversely with the rain intensity and will last longer in the wiped area than in the unwiped area. Reapplication is repeated as required to maintain repellent effectiveness.
B. The rain repellent system should not be operated on dry windows, as heavy undiluted solution will restrict window visibility. In the event of inadvertent dry window application do not operate the windshield wipers, as this tends to increase smearing. Also the rain repellent residues caused by application in dry weather or very light rain may cause staining or minor corrosion of the airplane skin. To prevent this any concentrated repellant or residue should be removed by a thorough fresh water rinse at the earliest opportunity, preferably within a few hours after exposure. Repellent residues allowed to dry or "cure" on the surface will require polishing with an approved aluminum polish to remove the stain. To remove residue from glass windows, use a repellent remover pad.
C. The rain repellent system consists of a pressurized container of rain repellent fluid, a container receptacle, a visual reservoir, a pressure gage, two solenoid valves, two nozzles, associated plumbing, and two electrical control circuits (Fig. 1 and 2).
May 01/98 30-43-0 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
2. Container and Receptacle
A. The rain repellent fluid is packaged in a pressurized disposable-type container (Fig. 1) which is replaced when empty. Each container has a self-sealing valve with a threaded boss for attaching the container to the system receptacle.
B. There are two types of fluid presently in use, type I and type III, which are packaged in different size containers. Type III is preferred due to its longer shelf life and repellent effectiveness. The two types of fluid are miscible, however when mixed the resultant solution tends to reflect the properties of the type I fluid. Therefore when converting from type I fluid to type III fluid it is recommended that the system be emptied of all type I fluid before introducing the type III fluid.
NOTE: The useful service life of type I rain repellent fluid is dependent upon the temperature to which it is exposed. Stored at room temperature, 65 to 75°F, a service life of about one year may be expected. Exposure to higher temperatures shortens the service life. The time rain repellent cans are installed on airplanes must be accredited to the one year useful service life storage period. Type III rain repellent fluid is not service life limited.
FLUID CONTAINER FLUID CONTENT CONTAINER WEIGHT CHARGING PRES. AT 70°F
TYPE VOLUME CHARGED DISCHARGED CHARGED DISCH.
I 793CC (26.8 fl oz) 425CC (14.4 fl oz) 30CC (1.0 fl oz) 795 gms (1 lb 12 oz) 237 gms (8.4 oz) 85 psia
III 936CC (32.0 fl oz) 505CC (17.0 fl oz) 30CC (1.0 fl oz) 955 gms 2 lbs 2 oz) 240 gms (8.5 oz) 85 psia
Contact with the rain repellent fluid can cause irritation of the skin or eyes. Precautions should be taken to prevent contact with the skin or eyes and to avoid breathing the fluid vapors.
D The fluid in rain repellent container P/N 65-38196-5 has a citrus scent.
E. The system receptacle has a valve actuating pin which opens the container valve as the container is attached to the receptacle. As the pin enters the valve assembly it is sealed by an O-ring in the valve prior to unseating of the valve to prevent fluid leakage. The pin is hollow and has inlet ports near the tip of the pin to allow fluid to enter the system from the container. The container and receptacle are mounted to the left of the second observer's station.
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