Citation Spring 2005
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Electric Windshield “Spare” Temp Sensors
— Joe Austin
This information was originally published on the Cessna Web site and applies to the 560XL, 650 (VII), 680, and 750s:
The electrically heated glass windshields used on the Citation X, Citation Excel, and Citation VII, have three integral temperature sensors designated as primary, secondary, and “spare.” The primary and secondary temperature sensors are connected to the windshield controller and are used to control the temperature of the windshield. The “spare” sensor is not used.
The term “spare” sensor, in this case, is misleading. In the event a primary or secondary temperature sensor fails, the “spare” sensor must NOT be used in their place. This is because of the way the windshield heating elements are wired.
There are three heating elements in each windshield. The outboard and center elements of one windshield and the inboard element of the other windshield are all heated and controlled by the same system. The “spare” temperature sensor is located with the inboard heating element (which is being heated and controlled by the opposite side system). So, if the “spare” sensor were to be used in place of a failed primary or secondary sensor, it would not be sensing the temperature of the heating elements that it is controlling, which can result in overheating of the windshield.
If a primary or secondary temperature sensor fails, the only option is to replace the windshield.
Battery Technology
— Karl Detweiler
Securaplane and Enersys have developed a true, solid lead acid main aircraft battery. This battery has many advantages. It can be stored fully charged for 24 months with no required maintenance.When in use, it only requires servicing every 18 months. Since it is a true, solid battery, it is rated non-hazardous and can be shipped by standard means.
A 30 month warranty (not pro-rated) begins at the time of installation, and is in addition to the 24 month shelf life. This battery should have the same life span as that of a NiCad battery. Manufacturers rate their batteries at full capacity when new.When Securaplane says its battery is a 25 amp/hour battery, it is rated 25 amp/hour at 80% of battery capacity, so a new Securaplane 25 amp/hour battery will have a 31 amp/hour performance.
The cost is approximately 1/2 that of a NiCad battery and there is no need to replace it. If cells are needed, the battery can be “re-blocked” for about 2/3 the cost of a new battery and has a 30 month warranty.
For further information contact Chris Gress at 800.228.4277 ext. 1664.
Trivia Question
— Joe Austin
The previous question was: On the 650, is there any maintenance manual limitation for checking the same axle tire diameter or circumference when installing a new tire on a wheel assembly?
The answer: Tire axle mates must have the same outer diameter within a tolerance of 0.25 inch (circumference within 0.78 inch). This will ensure that both tires will have the same contact area with the ground and will bear an equal share of the load. (ATA chapter 32-41-02)
This edition’s question is: Why is the forward pressure bulkhead at Fuselage Station 94.0 on most all of the Citation models? Why wouldn’t it be measured from the forward point of the radome?
To answer, please call Joe Austin at 800.525.2376.
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