Planning the Next C-130 Wing Durability Test

Transcription

1 Planning the Next C-130 Wing Durability Test Skip Ellsworth Lockheed Martin Aeronautics - Marietta C-130 Structural Integrity Skip.Ellsworth@lmco.com

2 Previous C-130 Wing Fatigue Tests Test Name C-130B Wing Fatigue Test ( ) C-130E Wing Fatigue Test ( ) C-130B/E Center Wing Fatigue Test ( ) C-130H Wing Durability Test ( ) Duration Simulated 20,000 Hours and 10,000 Landings Center Wing Simulated 23,000 Hours Outer Wing Simulated 30,000 Hours and 19,500 Landings Simulated 43,000 Hours and 7,317 Landings 60,000 Simulated Hours 45,000 Full Stop and 36,000 Touch and Go Landings 2

3 C-130H Wing Durability Test 1988 to 1992 C-130H Wing Durability Test consisted of a standard B/E center wing and FY 84 type outer wing 3

4 Why Another Test The Enhanced Service Life (ESL) Center Wing installed in C-130J production at SN 5619 and retrofitted to USAF C-130E/H SOF derivative aircraft has never been durability tested. Center wing service life estimates are between 67,500 and 120,000 EFH. The severity of this test will be approximately twice the severity of the C-130H Wing Durability Test. 4

5 USAF Objectives In accordance with AFI and MIL-STD-1530C, a full scale component test is required to validate the C-130 center and outer wing durability. The goal of the full scale wing durability test is to: Identify the design life of the ESL center wing and the outer wings. Identify the economic life of the ESL center wing and outer wings. Identify critical areas not previously identified. Provide a basis for special inspections and modifications. Obtain crack growth data to validate analysis and Equivalent Initial Flaw Size (EIFS) in support of risk analysis. 5

6 Benefit to the C-130 Operators Successful conduct of a C-130 Full-Scale Durability Test with an ESL Center Wing will benefit the C-130 Operators in several ways and include: Validation of the durability of the FY 84 outer wings and verification of the durability of the ESL center wing, potentially resulting in extended aircraft in-service times. Ensuring aircraft airworthiness, resulting in safe operating parameters for aircrew and cargo, to include troop and/or passenger transport. Validation of ESL center wing service life, which may result in recapitalization of critically required tactical airlift assets. Improved long-term aircraft availability. 6

7 Wing Durability Test Planning The goal is to test the ESL center wing and outer wing box structure based upon USAF C-130J usage until these box structures experience Widespread Fatigue Damage (WFD). In preparation of a future C-130 WDT, Lockheed Martin is: Developing the wing durability test plan Designing a C-130 wing test frame and load application system Conducting a spectrum clipping and truncation coupon test program Test Planning and Test Frame Design Test Prep Wing Durability Testing Tear Down Notional Timeline 7

8 USAF Test Aircraft USAF MC-130E was flown to LM Aero Marietta in November 2011 for future use in the wing durability test 8

9 USAF Test Aircraft MC-130E Tail Number (S/N 4080) AIRCAT Usage Summary Fuselage 22,258 Flight Hours Outer Wings replaced August 1985 Center Wing replaced July 1995 MEP 15z-0012 SOF Center Wing» 5,334 Flight Hours» 24,610 Equivalent Flight Hours (EFH)» 4.6 Average Severity Factor 9

10 Conversion of Aircraft Into the Test Configuration The forward fuselage forward of FS 245, and the aft fuselage and empennage aft of FS 737, will be de-mated and removed. The engines, outer wing leading edges, flaps, ailerons and other unessential systems will be removed from the wing box. The outer wings will be removed and replaced with low time wings taken from a decommissioned aircraft at Davis-Monthan Air Force Base 10

11 Test Planning Considerations Testing will be performed in Marietta, Georgia. The test frame will be of similar design to the 1988 wing fatigue test frame. Cabin pressures will be simulated on wing lower surface and MLG wheel well sidewalls with hydraulic actuators and pads. All loads will be applied symmetrically to the test article. Due to the anticipated service life of the ESL center wing, two sets of FY 84 design outer wings will be utilized over the duration of the test. It is anticipated that an ESL wing test to a minimum of 270,000 EFH with 9.6 million load points is required for the onset of WFD. 11

12 Instrumentation Approximately 700 strain gages will be installed on the test article The C-130 Loads/Environment Spectra Survey (L/ESS) instrumentation arrangement will be duplicated. Trend data monitoring will be used to assist inspections, anomaly investigations, and to predict potential failure locations. To facilitate trend monitoring, repeated reference cycles will be placed into the spectrum. 12

13 Test Spectrum Development The test will simulate USAF C-130J combat delivery and training utilization. MC-130E and MC-130H usage was also evaluated to ensure test spectrum sufficiently covers operations by legacy aircraft with an ESL center wing. USAF Structural Health Monitoring (SHM) data from 2010 through 2011 was evaluated for use in the test spectrum Training operations by C-130J AETC squadron at Little Rock. Combat delivery operations by C-130J AMC squadrons at Little Rock and Dyess. Air Force Central (AFCENT) operations by C-130J squadron in Afghanistan. USAF Europe (USAFE) operations by C-130J squadron based in Ramstein. MC-130E AFRC squadron at Eglin, MC-130H AFSOC squadrons at Hurlburt, Kadena and Mildenhall, and MC-130H AETC squadron at Kirtland. 13

14 Test Spectrum Development The preliminary ESL wing durability test spectrum severity factor on the lower surface at the wing root is approximately 4.9 The actual test severity will be determined once the spectrum has been approved by the USAF and the jack loads and sequences have been defined. Comparison of C-130H and C-130J Wing Durability Test Spectrums Test Number of Missions Number of Flights Flight Hours EFH Total Landings Average Landings/FH Number of Cycles C-130H WDT C-130J ESL WDT 13 7,351 20,000 40,000 26, , ,345 18,209 89,959 24, ~ 1,600,000 14

15 Conclusion Durability Testing is a vital component in the sustainment of the C-130 fleet. The test will validate the analytical predictions of wing durability, define the point of onset of WFD and establish the Service Life of the ESL center wing box structure. This will be planned as a cost effective test. The test plan will draw from the experience of the previous C-130 wing durability tests, and from other Lockheed Martin full scale aircraft fatigue test programs. 15

16