Subsystem

Time to initial

failure (Hrs.)

Time to next failure (TNF)

(Hrs.)

Air drilling system

255

9 + WEIB (240, 0.376)

Hoisting system

679

4 + EXPO (606)

Power system

1963

2 + WEIB (289, 0.339)

Well control system

240

412 + WEIB (121, 0.235)

Well monitoring system

2022

UNIF (122, 2.92e+003)

Circulating system

5116

−0.001 + EXPO (77.7)

Mechanical handling system

4836

5116

Top drive system

413

2 + WEIB (320, 0.339)