- 90 - 



shown in Figure V-A. The chamber on the arm sensor of dPA was loaded 

 (a) and then allov/ed to communicate with the center sensor chamber 

 (B) . The differential transducer correctly reported zero difference 

 in pressure. When the entire system was bled (C) , the transducer 

 briefly indicated a greater pressure on the arm side. The arm was 

 re-back-filled to be safe. 



3. Static Calibration Results 



The calibration results for each of the four differential 

 pressure and the absolute pressure transducers as found during the 

 pre-FRF calibration are shown in Figures V-5 (a) through (e) . 

 Differential transducers dP2, dP3, dP4, and the absolute transducer 

 each demonstrated acceptable one-to-one reporting of the loads 

 applied. DPI, however, is significantly biased. The problem was 

 attributed to the transducer itself, since a similar error appeared 

 during the first calibration. The zero-differential value of dPl was 

 also consistently high (5 to 7 volts as compared to 2.5 volts, as 

 ordered); and unlike the other transducers, it demonstrated 

 sensitivity to excitation voltage as is discussed in Section V.C.4. 

 This malfunction did not appear until just before the scheduled 

 testing was to begin at CERC and time limitations did not allow for 

 its immediate repair. The calibration results of the first 

 investigation for the absolute transducer and dP2, dP3, and dP4 are 

 identical to those of the second. 



