Advisory Maintenance/Operators Group

Transcription

1 : Scottsdale, Arizona Advisory Maintenance/Operators Group 1

2 Mission Statement: To provide an independent technical and operational maintenance forum to ensure the continuing quality and safety of the Honeywell/Garrett TPE series, aircraft gas turbine, turboprop engines., Inc. Non-profit organization Incorporated in the state of Missouri 2

3 Officers Chairman: Dave Corwin - 3 year term Secretary/Treasurer: Barry Martin Board of Directors: Don Murdoch, Pat Earl, Clark Blumberg, Barry Martin, Dave Corwin Bylaws requirement: - Additional members require 2/3 vote by existing members 3

4 Website Action Committee: Pat Earl, Clark Blumberg Website maintenance and update - Members and contact info? - Service difficulty reports? - Comments for NPRM s affecting TPE? - Maintenance tips? - Others? 4

5 A.D New Cycle Counting Method SAIB NE Continued partial cycle counting required for ALL operators 5

6 A.D New Cycle Counting Method SAIB NE Log entry stating AD Not Applicable is incorrect 6

7 TPE engines with hydraulic torque sensors Action Committee: Mike Straus, Mike Croye, Matt Hart, Peter Pox, Bob Hancock, Dave Corwin Draft SPECIAL AIRWORTHINESS INFORMATION BULLETIN Aircraft Certification Service Washington, DC This is information only. Recommendations aren t mandatory. Introduction Background U.S. Department of Transportation Federal Aviation Administration NE-06-xx October 24, 2006 This Special Airworthiness Information Bulletin (SAIB) alerts owners and operators of, and maintenance facilities working on Honeywell International Inc. TPE series turboprop engines with hydraulic torque sensors. This SAIB informs the public of recent NTS malfunctions experienced during in-flight maintenance tests. This SAIB requests that maintenance facilities contact the LAACO if these incidents occur. This SAIB recommends that a calibrated trip check be accomplished before and after the in-flight NTS maintenance check. This recommends that the engine spool down time be recorded after the in-flight NTS maintenance test. Two recent NTS malfunctions occurred in August, 2006 at two different Honeywell authorized maintenance facilities. Both Background incidents occurred on MU-2 aircraft Two recent NTS malfunctions occurred in August, 2006 at two different Honeywell authorized maintenance facilities. Both incidents occurred on MU-2 aircraft and produced excessive yaws within two seconds after shutting down the tested engine. Both engines involved in the incidents were calibrated to the required negative torque trip points of 28 to 35 in-lbs. After the incidents both engines trip points were unusually much higher after the in-flight NTS maintenance check than their original set trip point. These unusually higher trip points were experienced during hand tripping and post test torque sensor calibration checks on the mini-test stand. Recommendations for maintenance facilities to notify the LAACO...The FAA is very interested in these and similar incidents that might occur. One of the two produced a sharp roll of approximately 60 degrees and regained level flight after the feather valve was activated. The other incident NTS d on its own after a delayed response and after producing its yaw. Both incidents had either a thoroughly briefed maintenance technician or a copilot in the right seat. Recommendations for maintenance facilities to notify the LAACO: Both maintenances facilities did not report the incidents to the FAA because the incidents occurred during maintenance. Subsequent to these incidents, normal troubleshooting and maintenance corrective action occurred. The FAA is very interested in these and similar incidents that might occur. Please contact the LAACO if hand tripping does not verify the calibrated negative torque trip point after in-flight NTS maintenance check. The LAACO requests that discrepant components be retained for additional examination. 7

8 TPE engines with hydraulic torque sensors Action Committee: Mike Straus, Mike Croye, Matt Hart, Peter Pox, Bob Hancock, Dave Corwin FVTP in-lbs (GR) = Trip weight for prop at 12 ( D) at Point D FVTP = Feathering valve trip point with pressure side of torque sensor capped GR = Gear ratio for engine (1591 RPM: 26:1 gear ratio; 2000 RPM: 20:1 gear ratio) D = Distance (feet) from hub where weights are placed called Point D (3) Verifying this calculated trip point with a special hand trip tool and hand trip procedure Hand Trip Procedure The procedure simulates negative torque sensing and activates the feathering mechanism by holding the engine s rotor assembly and pulling the propeller. The procedure is similar to ground checking the NTS Lockout and Propeller Governor Reset Check as described in the engine maintenance manual Section 2. D. as follows: (1) Remove the starter/generator in-flight NTS test: (2) Engine- not running (3) Speed Lever- Low (4) Power Lever- Flight Idle (5) Hold the impeller from the engine s intake (6) If equipped, place NTS test switch ON (applies only to 1591 RPM engines; proceed to Step 7 for 2000 RPM engines); some aircraft, such as the MU-2, have no button to energize (open) the negative torque check-out valve/ actuator. Therefore, the valve must be activated manually with a voltage source from under the cowl. (7) Unfeather pump- activate (8) NTS check light ON ; some aircraft have no NTS light, the NTS switch is tied to the Beta Light (9) Apply a known force and move prop in the normal direction of rotation (10) Record the known force when NTS light extinguishes (this should occur at the same time the unfeather pump changes tone (pump pressure is dumped to case)) (11) Removing the force on the prop will move the torque sensor in the positive torque direction and reload the unfeather pump pressure. Recommended additional procedures after (1) Retest the verified trip in Step 3 after the test flight to ensure that the hand trip point is unchanged even if the flight test is passed. Recommended additional procedures during the in-flight NTS test: (1) Record the amount of time for the engine to decelerate to approximately 35% RPM. Recommended additional procedures after the in-flight NTS test: (1) Retest the verified trip in Step 3 after the test flight to ensure that the hand trip point is unchanged even if the flight test is passed. Aircraft Sensitivity to in-flight NTS testing The FAA believes that certain aircraft with the TPE engine installed may react and be substantially more sensitive to an NTS malfunction. Therefore, some pilots will be more aware of excessive yaw in those aircraft 8

9 TPE engines with hydraulic torque sensors Action Committee: Mike Straus, Mike Croye, Matt Hart, Peter Pox, Bob Hancock, Dave Corwin Setting positive torque and NTS trip Coupler position and spline wear 9

10 Gentlemen, Dave TPE engines with hydraulic torque sensors Action Committee: Mike Straus, Mike Croye, Matt Hart, Peter Pox, Bob Hancock, Dave Corwin recommendations for Draft SAIB 10 I have attached the latest version of the FAA s SAIB regarding NTS shift and malfunction. After discussion with several of you and input received I will send our recommendation to Joe Costa which will be for the maintenance shop to record the Torque Sensor final Positive and Negative pressures after setting the NTS IAW the Maintenance Manuals along with the trip setting with the dummy positive regulated pressure input applied and also with the dummy positive regulated pressure capped off. Capping off the dummy input pressure typically results in an increase of the torque required to trip the NTS. Recommend deleting the proposed Hand Trip Procedure in the SAIB and in the event of a problem of the NTS system during flight check, add the requirement to reinstall the NTS mini cart as specified in the maintenance manual and recheck the previously recorded Positive pressure, Negative pressure and NTS in-lb trip setting points to confirm if a shift has taken place. This procedure will give a base line of 40 years of history and approved manual procedures to compare with the accumulated data and avoid potential hazards. We believe that the majority of shifts in the positive and negative torque setting after NTS flight check are due to undetected spline wear of the Torsion Shaft, Coupler and or High Speed Pinion. Shop reports of faults found with the NTS system IAW this SAIB will give the FAA valuable information to identify other problem areas. Thanks for all your help.

11 AD Woodward FCU Mod and Spline Inspection Action Committee: Bob Hancock, Bill Wolff, Paul Leiss, Dave Campbell, Mike Straus, Wes Wiwcharuk, Don Murdoch Spline disengagement results in uncontrolled high fuel flow rate Engine still on locks = explosive overspeed 11

12 AD Woodward FCU Mod and Spline Inspection Action Committee: Bob Hancock, Bill Wolff, Paul Leiss, Dave Campbell, Mike Straus, Wes Wiwcharuk, Don Murdoch AD requires revision - Include FCU assemblies /-13 - No current modified assembly for TPE-1/-2/-2UA engines 1000 hour Spline Inspection Requirement - Problem? - Lack of special tooling in the field - Possibility for mis-assembly by untrained personnel Recommendations for an AMOC until AD revised - Fuel lubricity evaluation SIL P Extend spline inspection to HSI event - Allow installation of serviceable non-modified units 12

13 Idler Bearing Failures: and Action Committee: Peter Pox, Clark Blumberg, Matt Hart, Dave Corwin, Chris Kelner, Bob Hancock Failure results in in-flight engine out Recommend reducing the 9000 hour replacement schedule? ~ 3600 hour replacement? ~ 7100 hour replacement? 13

14 Torque Sensor Gear Wear Heavy FCU drive train gear wear noted on torque sensor (P/N ). Alignment? Material? 14

15 Removal of Turbine Wheel Rivet Hole Repairs Rivet hole repair removed from IRM 72-IR-10 for TPE-1 thru 6 Possible Reasons - Continued wheel failure due to extended rivet hole cracking? - Improper repair procedure? - Difficulty in detecting rivet hole cracking with standard FPI methods? - (Remaining dirt and debris in hole obscure indication) - Inspection by non-certified technicians? - (ASTM Level 2 certified required) Reports from field indicate that repaired rivet holes are LESS SUSCEPTIBLE to continued cracking FAA s position? 15

16 7,000 Hour TBO 9 Year Requirements Action Committee: Wes Wiwcharuk R31: TPE-10/-11 Engines Engines not sustaining utilization of at least 800 operating hours per year must also satisfy the then latest minimum configuration requirements for these programs at intervals of not more than 9 years. Allows 9 years from the date a service bulletin is added to for compliance? R27: TPE-12 Engines Except for alert service bulletins, any new service bulletin added to table 5 or 6 must be complied with at the next engine overhaul or CAM inspection based on the currently elected TBO or CAM interval or within 9 years of last access to the affected parts, whichever occurs first. No time allowance for compliance with future service bulletins if last access was beyond 9 years? 16

17 Minimum Performance Requirements? Results of continued operation with deteriorated performance Typical configuration for TPE-1 thru -6 First Stator Second Stator 17

18 Minimum Performance Requirements? Typical configuration for TPE-1 thru -6 Scoring of 2 nd T-wheel due to contact with failed 2 nd stator Loss of Rim 18

19 Minimum Performance Requirements? Final result: Uncontained Failure Power degradation...who draws the line? - Engine OEM - Airframe OEM - Maintenance - Pilot - FAA Uncontained Failure 19

20 New TPE-10/-11 2 nd Stage Blade Criteria Old chord dimension = New chord dimension = B F A 20

21 Helical Twist Gears on -11/-12 Engines Service Bulletin A & A Field reports on gear wear and possible high speed pinion failures? - Bull gear rim rubbing - Problems? 21

22 Logistical Problems Action Committee: David Augustin, David Finley, Rob Louviaux, Clark Blumberg TPE-5/-6 Bendix FCU overhaul and repair - Problem: single source vendor Other logistical/parts problems? - Jetstream - Mitsubishi - Twin Commander - Fairchild 22

23 Carbon Seals Reduction in bellows spring height after overhaul - Problem: rear carbon seal leaks 23

24 Standardization of Traceability Sheets Suggested by: George Smith Suggested format Facility Name 24

25 Comments and Questions 25