Failure Analysis of a Cam Gear in the Torquemeter Assembly of a Turboprop Engine
- PDF / 1,521,734 Bytes
- 6 Pages / 595.276 x 790.866 pts Page_size
- 60 Downloads / 209 Views
CASE HISTORY—PEER-REVIEWED
Failure Analysis of a Cam Gear in the Torquemeter Assembly of a Turboprop Engine R. K. Mishra . D. Arul Kumaresan . C. Jagadish Babu . Vinay Kumar
Submitted: 5 February 2019 ASM International 2019
Abstract Failure analysis of a cam gear in the torquemeter assembly of a turboprop engine has been carried out to determine the root cause of the failure so that remedial measures can be adopted to prevent such failures in flight. During flight, one of the engine torques and turbine temperatures started fluctuating leading to the shutting off of the engine. Detailed defect investigation reveals that improper assembly and mounting of the gear have led to the shearing off gear teeth causing torque fluctuation. Keywords Turboprop engine Torquemeter Cam gear Fractography Fatigue failure
Introduction Turboprop engine is a gas turbine engine, which derives its thrust through a propeller driven by the turbine shaft through a speed reducing system. Since the efficiency of the propeller decreases with an increase in its rotational speed, a heavy reduction gear mechanism to maintain the low propeller speed makes the turboprop engine more complicated and heavier than a turbojet engine of equal size and power. The propulsive efficiency of a turboprop engine decreases as flight speed increases; the engine delivers more thrust at low subsonic airspeeds. Due to its large diameter, the propeller accelerates a large mass of air at low airspeed and this enables the engine to offer best performance during takeoff and climb phase. This lowspeed performance facilitates the aircrafts propelled by
turboprop engines to carry heavier payloads, making them the ideal choice for cargo and military commuter aircraft worldwide [1–3]. Torquemeter assembly and reduction gear assembly are important and unique to turboprop engine compared to turbojet and turbofan engines [4–6]. The torquemeter assembly is located between the power section and reduction gear assemblies and facilitates the transmission and measurement of shaft output from the power section of the engine to the reduction gear assembly. The reduction gear assembly changes the high rpm, low torque of the turbine output to the low rpm and high torque necessary for efficient propeller operation [7, 8]. To carry out these activities, these assemblies are fitted with number of gears and bearings apart from various sensors. Therefore, these mechanical systems have complicated assemblies and functionality of gears and bearings, experience variable loadings acting on transmission shafts, and suffer tear and wear in service. These factors make these systems highly prone for various defects and failures in service leading to premature withdrawals of engine. Any defect or failure in aeroengine not only affects the fleet management but also imposes life restriction on engine usage and huge financial burden to the operators. The present paper analyzes the failure of cam gear in the torquemeter assembly of a turboprop engine during flight. Improper assembly procedu
Data Loading...
