AEROGRAPHER'S MATE 3 & 2 



The equipment is issued ready for use and 

 comes stowed in a carrying case containing 

 a spare wind speed transmitter and a spare 

 wind vane. The instrument should always be 

 replaced in this carrying case after use. Special 

 care should be taken in removing the anemom- 

 eter from the case and replacing it in the case 

 because damage may easily result to the wind 

 vane section. 



MAINTENANCE 



In the care and maintenance of Wind 

 Measuring Set AN/PMQ-3( ), no special service 

 tools are needed. In inspecting the equipment, 

 make certain that the turbine and vane are 

 free to rotate and that there is pointer move- 

 ment when the turbine is rotated. Check for 

 freeness by holding the instrument in its 

 operating position and walking at a moderate 

 rate of speed in an area where there is no 

 air movement. If the vane assumes the correct 

 position and there is a speed indication on 

 both scales, it is probable that the instrument 

 is in a satisfactory condition. 



If trouble develops in the system, refer to 

 table 3-2. This table lists troubles, along with 



possible causes, and their remedies. Procedures 

 to replace or repair a component when found 

 to be malfunctioning are as follows: 



1. Wind speed transmitter. — To replace the 

 wind speed transmitter (fig. 3-1), grasp the 

 transmitter by its cover (never the cage) and 

 give it a slight twist in a counterclockwise 

 direction (looking down on the instrument) and 

 pull it straight off. Remove the spare transmitter 

 from the case in a like manner. Install the 

 spare transmitter by reversing the above pro- 

 cedure, making sure that the unit is securely 

 locked in position. 



2. Wind speed indicator. — See technical 

 manual (NA50-PMQ3C-1) for details of pro- 

 cedure. If physical damage is not visible, and 

 as a defective indication may be caused by 

 another component, do not discard the unit 

 until its condition has been proved unsatisfactory 

 by a requisitioned replacement. 



3. Trigger and switch assembly. — See tech- 

 nical manual (NA50-PMQ3C-1) for details of 

 procedure. If physical damage is not visible, 

 and as a defective indication may be caused 



Table 3-2.— Troubles and remedies (wind speed system— AN/PMQ-3( )) 



Trouble 



Probable cause 



Remedy 



No pointer movement 0-60 

 range or 0-15 range. 



Defective speed indicator. . . 



Replace detector. 

 Replace indicator. 



No pointer movement 0-60 

 range only. 



Defective speed indicator. . . 



Replace indicator. 



No pointer movement 0-15 

 range only. 



Defective switch or defective 

 speed indicator. 



Connect the terminals 

 of the switch to- 

 gether; if indication 

 is obtained, replace 

 trigger assembly. If 

 no indication is ob- 

 tained, replace 

 indicator. 



Pointer does not rest on 

 zero when turbine is 

 stationary. 



Speed indicator not properly 

 zeroed. 



Turn zero set adjust- 

 ment located on the 

 front of the indicator. 



Sluggish pointer 

 movement. 



Dirty or damaged speed 

 indicator. 



Replace indicator. 



38 



