Force sensing bolt for a torque measurement system on a gearbox of a gas turbine engine

A turboshaft engine transmission system with a torque measurement system, the turboshaft engine transmission system comprising:

• a front housing;
• a rear housing;
• a mating flange axially interposed between the front and rear housings, the mating flange defining a sensing bolt hole;
• assembly bolts disposed to assemble the front and rear housings to the mating flange with a preload sufficient to maintain assembly during engine operational conditions;
• a sensing bolt installed in the sensing bolt hole to measure forces exerted on the mating flange by the front and rear housings and to generate a signal reflective of the forces;
• and
• an engine controller coupled to the sensing bolt and configured to calculate engine output torque from the signal.

A method of calculating engine output torque in a turboshaft engine transmission system with a torque measurement system, the method comprising:

• assembling front and rear housings to a mating flange with a preload sufficient to maintain assembly during operational conditions;
• installing sensing bolts in sensing bolt holes of the mating flange to measure forces exerted on the mating flange by the front and rear housings and to generate signals reflective of the forces;
• calibrating the sensing bolts;
• and
• calculating, in an engine controller coupled to the sensing bolts following the calibrating, the engine output torque from the signals.