Greenvalley285 Posted December 21, 2016 Report Share Posted December 21, 2016 Engine Topping Check in Huey II helicopters , after maintenance of helicopter is an intricate procedure. I will straight go to my question. TM 55-1520-242-MTF describes topping check. The manoeuvre requires climbing to topping altitude, pull max allowable torque, and see if N2 drops from 6600 to 6400 or not. Dropping of N2 is evidence that, Engine has topped, at its max performance, and cannot be expected to provide any additional power. The check is, engine must pull minimum torque, as calculated from TM, while N2 also drops. What if, helicopter pull require torque at Topping Altitude, but at the same time, N2 does not drop. Should we take it as, Engine has passed Topping Check, or adjust Fuel from Trimmer screw (actually adjusting N1). Quote Link to comment Share on other sites More sharing options...
iChris Posted December 23, 2016 Report Share Posted December 23, 2016 (edited) What if, helicopter pull require torque at Topping Altitude, but at the same time, N2 does not drop. Should we take it as, Engine has passed Topping Check, or adjust Fuel from Trimmer screw (actually adjusting N1). No, it has not necessarily passed the topping check. Successfully completed may require additional adjustments to achieve the desired results. The term “topping check” is a generic term use to describe different types of engine performance checks. Its meaning often differs between manufacturers and/or engine types. This has led to the confusion. Therefore, you must always reference the specific engine maintenance manual. From the manual: If 10,000 feet pressure altitude is reached prior to N2 droops, note the torque at 10,000 feet pressure altitude and temperature to ensure that the fuel control is not over trimmed. If necessary, adjust IAW TM 55-2840-229-23. If fuel control is not over trimmed (in excess of 3 PSI required torque) engine topping must be deferred until temperature conditions improve. If N1 increases as N2 droops from 6600 to 6500 RPM, the droop cam is probably worn or out of adjustment and the engine is not “topping” out at 6600 RPM and should be corrected. If N1 changes as N2 droops from 6400 to 6200 RPM, the engine is probably not at maximum power and the droop cam must be adjusted before an accurate topping check can be accomplished. In this case, you’re comparing N1, EGT, and torque at an ambient pressure altitude and OAT, against a chart for the minimum spec engine. Basically, measuring the engine against the standard one used to calculate the performance of the aircraft. We also covered a lot of this in one of your prior post (Link below: Greenvalley285)Relationship of Indicated Torque with Engine Power available in T-53 Engines Edited December 23, 2016 by iChris Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.