Summary report of the turboprop test chamber acceptance tests conducted on 27 April to 8 May 1964

Abstract

Acceptance testing of the Turboprop Test Chamber was conducted during the weeks of 27 April and 4 May 1964. The tests were conducted by personnel from the Overhaul and Repair Department, Alameda Naval Air Station, from the Bureau of Naval Weapons Fleet Readiness Represent­ative, Pacific and from the USNPGS Department of Aeronautics. The power plant utilized for correlating purposes for a T-56-lOW turboprop engine, recently overhauled at NAS Alameda while the propeller was the Hamilton Standard model required for this engine. The test data reveal satisfactory correlation of the engine performance data with the Alameda test results. The discrepancies that do appear are the result of errors in the instrumentation system and do not present a major problem. All of the major facility systems function satisfactorily except the oil supply system and the chamber lighting fixtures. Engine starting and control systems were adequate although somewhat different from the designs utilized in the NAVWEPS specifica­tions for this engine. The engine support stand and thrust measuring assembly were found to be structurally sound and functioned satisfactorily. The propeller orifice assembly did not induce prohibitive vibrational stresses as was anticipated. However, the vibrational loads did cause the majority of the orifice retaining bolts to loosen during the test sequence. Three bolts were found beneath the test stand; these could have caused object damage to the engine. The major areas of discrepancy are the engine oil supply system and the test chamber lighting fixtures. The engine oil system as designed could not satisfy the requirements for the T-56 series engine. It was necessary to re-route the oil by-pass system, to obtain a more precise control of the engine oil supply and pressure, and to provide a method to heat the oil for operation of the engine at high power set­tings. The system as temporarily modified, did function adequately during the test period. The lighting fixtures mounted on swivel joint bases oscillated vio­lently when operating the engine at Idle power. One fixture above the engine broke loose during this short period and was blown clear of the engine stand by the propeller air stream. All ceiling-mounted light fixtures were removed from the chamber before further engine operation. The acoustic survey revealed that the acoustic paneling in the in­ let and the exhaust passages functioned satisfactorily. However, the Sound Pressure Level reduction across the chamber front double-doors did not meet the specified limits. Corrective action is required to (1) provide adequate and safe lighting in the test chamber, (2) re-design and install an oil supply system compatible for operation with the T-56 engine, and (3) provide positive locking devices on all bolted fixtures in the test chambers.