Item design stability mil.

[Shears]

C6.3.2.1. For all secondary items, the assigned IMM shall be the authority for
approving all returns of unserviceable materiel to designated depot maintenance or
wholesale distribution activities.
Approval of unserviceable returns should be based on:
Item design stability and impact of technological changes.

[muzungu]

Так и переводите - стабильность конструкции изделия

[overdoze]

устоявшийся/отлаженный/зрелый/матерый дизайн (или конструкция, или даже характеристики)

[Rengo]

мб неизменность конструкции
"Design stability" means that minimal to no design changes are necessary after major design reviews

[muzungu]

В том и дело, что конструкция будет меняться, но надо, чтобы не сильно. Здесь на стр. 7 пример http://www.gao.gov/assets/150/141720.pdf
MODIFICATIONS TO HMMWV REVEALED
LACK OF DESIGN STABILITY
One prerequisite for a multiyear contract is that the system design be stable. Design stability diminishes the prospect of a retrofit program. The HMMWV prototype design lacked this stability, as evidenced by the extensive modifications being made to the production vehicles to correct
hardware deficiencies attributed to the prototype design.
Included among the numerous modifications were
--shortening the chassis frame,
--modifying the tires,
--changing the exhaust system,
--modifying the engine accessory drive pulleys and mounting
brackets,
--redesigning the front axle half shafts,
o-redesigning the front prop shaft,
--modifying the torque converter ratio,
--changing the axle ratio,

[Rengo]

постоянство конструкции тогда - оно предполагает внесение какого-то минимума изменений