EHM Pilot Guide for P&WC's JT15D, PW300, PW500 & PW600 Engines

Transcription

1 EHM Pilot Guide for P&WC's JT15D, PW300, PW500 & PW600 Engines The Exclusive Pratt & Whitney Canada Designated EHM provider for all P&WC engines Contact: (North America) (International) For EHM Data: (Trend Fax Line)

2 THE AIM OF ENGINE HEALTH MONITORING (EHM) 1. Your safety 2. Money saving for your company - Lower Hot Section Cost by early problem detection - Better maintenance planning (less down-time) - Less possibility of a flight abort - Increase dispatch reliability HOW DOES IT WORK? By normalizing the flight data to a standard day (sea level) condition and by taking into account your stabilized cruise power setting, we can compare the performance of your Pratt & Whitney Canada Corp. ("P&WC") JT15D, PW300, PW500 and PW600 series engine on a flight to flight basis. HOW ACCURATE SHOULD IT BE? After normalization of data, performance is assessed by a change of as little as 0.1% in N 2, 1 C in ITT and 1 pph in W F for graphic output. HOW DIFFICULT IS THIS TO ACHIEVE? If you look at an EHM trend graph (see Figure 1), you will notice that each value fluctuates. This fluctuation is referred to as "noise" or "scatter". Part of it is caused by the tolerance build-up in the instrumentation/sensor and part by human or reading/recording error. A large amount of it can be eliminated (see Figures 2, 3, 4 and 5). CAMP Systems Int l is the exclusive provider of EHM. Only Designated Analysis Centers (DAC) such as CAMP Systems Int'l that are certified and subscribe to EHM are recognized and approved by Pratt & Whitney Canada Corp. for the maintenance, warranty and extended warranty benefits which Engine Health Monitoring can provide. JT15D, PW300, PW500 and PW600 are trademarks of Pratt &Whitney Canada Corp. Recommendations to operators as part of Engine Health Monitoring (EHM) are advisory and do not replace regular maintenance required by the Original Equipment Manufacturer (OEM) and documented in the applicable Maintenance Manuals (MM), Service Bulletins (SB) or contracts. It is the responsibility of the operator to maintain Airworthiness of their aircraft and to carry out maintenance actions recommended by the Designated Analysis Center (DAC). Further, any information provided in this communication remains subject to the terms and conditions set forth in any applicable agreements.

3 FIGURE 1

4 FIGURE 2 P&WC JT15D TYPICAL ENGINE MISREAD VARIABLES

5 FIGURE 3 P&WC PW300 TYPICAL ENGINE MISREAD VARIABLES

6 FIGURE 4 P&WC PW500 TYPICAL ENGINE MISREAD VARIABLES

7 FIGURE 5 P&WC PW600 TYPICAL ENGINE MISREAD VARIABLES

8 HOW CAN WE REDUCE THE NOISE? Be careful 1. Let the engine parameters stabilize in the selected cruise leg of your flight (about 5 minutes into cruise) and don't touch the power levers, otherwise you will have to wait another 5 minutes. 2. Standardize on the cruise condition for EHM. The power used for computation of EHM is the power for aircraft propulsion only; none of the auxiliary power extracted from the engine is accounted for. Therefore to obtain continuity from flight to flight, the same amount of auxiliary power (generator/alternator, hydraulic, air conditioning, anti-ice and bleed air) should be extracted from the engine each time. 3. Insure actual readings are taken rather than "targets"; rarely will an engine stabilize at a "target" and this can have a major effect on "noise". You might, if chosen, initially select a reference power setting but during the 5 minutes stabilization period, you should let the engine power drift away from that initial setting. It doesn't matter if the engine's power indications are mismatched since the CAMP EHM application will compensate as long as accurate parameters are provided. 4. Try to avoid parallax errors. To minimize this, the same cockpit seat should be used to record the EHM data. 5. Try to read the variables in a reasonable time frame for each engine separately. a) The Fan Speed (N 1) should be read to 1/10 of 1%. b) The Turbine Speed (N 2) should be read to 1/10 of 1%. c) The Interturbine Temperature (ITT) should be read as close as possible. d) The Fuel Flow (W F) to the closest 5 pph. e) The ECS Bleed and Anti-Icing status (PW305A and PW305B only). then read: f) The Indicated Outside Air Temperature (IOAT) to the closest 1 C; be careful of negative temperatures. (See Note 1) g) The Pressure Altitude (P.Alt) to the closest 10 feet, after resetting to 29.92"Hg, or as accurate as the instrument allows. (Do not write down flight level) h) The Indicated AirSpeed to the closest 5 knots. (See Note 2) Finally, read the other engine variables as per a), b), c), d) and e) above. See Figures 2 (JT15D), 3 (PW300), 4 (PW500) and 5 (PW600), and notice the error that is created by misreading instrumentation. NOTE 1: On aircraft equipped with Air Data Computer (ADC), you should identify the source of IOAT indication when proceeding with manual trend recording: Total Air Temperature (TAT) or Static Air Temperature (SAT). NOTE 2: On aircraft equipped with Air Data Computer (ADC), you should use the Calibrated Airspeed (CAS) indication when proceeding with manual trend recording. AT WHICH POWER SETTING AND AT WHICH ALTITUDE DO I TAKE THE READING? The CAMP EHM application will correct for a normal range of cruise power setting and altitude. Be careful! The application does not fully correct for the cabin pressurization system; much more energy is extracted from an engine with a selected cabin pressure of 8,000 ft. flying at 24,000 feet than a selected cabin pressure of 8,000 feet flying at 36,000 feet. Because of that, when using bleed air, you should not have more than ±2,000 (best) to ±5,000 (extreme) feet of altitude variation from a reference cruise altitude as established by your operations personnel. Accurate recording in flight of 11 (15 for PW305A/PW305B) cockpit instruments by the pilots is all that is required. At your maintenance base, the maintenance personnel will input and plot your flight cruise data daily and look for changes. Remember, the CAMP EHM application is only as good as the data entry and interpretation.