Bearing Strength Assessment PLR & PCN

Transcription

1 1 LEISMER AIRPORT (Airport code CET2, Canada) Bearing Strength Assessment PLR & PCN Report APMS October 21, 2011 APMS Stationsweg 51, Velsen-Zuid 1981 BA, the Netherlands Phone: + 31 (0) ; apms@filarski.com

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3 3 Table of Contents 1.0 INTRODUCTION Statement Definitions and applicable documents LEIUSMER AIRPORT (CET2), Canada General Spring Reduction Factor CBR subsoil Runway CALCULATION Maximum allowable tire pressure Runway bearing strength (Transport Canada practice) Runway bearing strength PLR Runway bearing strength PCN (International practice; ICAO) Runway bearing strength PCN Check up on calculated PLR and PCN Aircraft data ALR calculation (TC) ACN calculation (TC) CAN calculation (FAA) PRESENTATION Transport Canada presentation International (ICAO) presentation SUMMARY Runway bearing strength (PLR) Runway bearing strength (PCN) page Attachements: Attachment A: ACN-PCN method (ICAO, Annex 14) Attachment B: CBR test results by CBR Techn. Inc Attachment C: BAe specification.. 20 Note: This Report contains 21 pages.

4 4 1.0 INTRODUCTION. 1.1 Statement Airfield Pavement Management Systems (APMS, Velsen-Zuid, the Netherlands) executes test procedures and calculations with respect to the assessment of the usability of paved and unpaved (gravel) runways for aircraft operations. This report has been compiled with great care and to the best knowledge and understanding. However, APMS does not accept any responsibility for any errors or misprints in this report. The content of this report shall not lead to any juridical obligations whatsoever. 1.2 Definitions and applicable documents PCN: A Pavement Classification Number (PCN) is a number that express the bearing strength of a pavement for unrestricted aircraft operations (ICAO). PLR: A Pavement Load Rating (PLR) is a number expressing the bearing strength of a pavement for unrestricted aircraft operations (Transport Canada). The following documents from Transport Canada (TC), the Boeing company, CBR Technology Inc., British Aerospace and the International Civil Aviation Organization (ICAO) are applicable: - TC: TP 6348E, Engineering Reference Document ERD No: 133, Transport Canada and ICAO Methods for Reporting Airport Pavement Bearing Strengths, July 2002; - TC: TP 1848, Airport Pavement Evaluation Bearing Strength, AK , September 1987; - TC: ASG-19, Manual of Pavement Structural Design (AK-68-12), July 1992; - TC: Gravel Runway Surface Measurements and Aircraft Certification Requirements, Issue 1, June 30, 1997; - CBR Technology Inc.: CBR test results of Leismer Airfield, July 17, 2011; - Boeing Company: Document Number D , December 1969; - British Aerospace: BAe146 Airplane Characteristics, January, 1985; - ICAO: Annex 14, Aerodromes, Volume I, Aerodrome Design and Operations, Fourth Edition, July 2004.

5 5 2.0 LEISMER AIRPORT (CET2), Canada. 2.1 General Leismer Airport (CET2) is located in Alberta, Canada. The airport has a surface treated gravel runway RW The coordinates of the Aerodrome Reference Point (ARP) are: N and W. No official publication could be found (Oct. 24, 2011). The content of the information on this page has been derived from: Airport Name Conklin (Leismer) Airport Category Registered Aerodrome PPR - Prior Permission Required Nearest Community Conklin, eight miles to the east of the aerodrome Province: ALBERTA Coordinates Latitude (N): Longitude (W): Listed in Canada Flight Supplement Yes Airport ident. CET2 Appears on a VFR Navigation Chart Yes Airport Elevation 1930 Magnetic Variation 17E Runway (Main): Number: Length: 5000 ft Width: 100 ft Surface Gravel. Limited maintenance. Night Flying No Maintained Year Round No Radio Communications Unicom MHz within 5 nm and 4900 feet ASL Telephone on the Airport No Customs Airport Entry No CANPASS No Fees on Private Aircraft Landing $: 0.00 Terminal $: 0.00 Parking $: 0.00 Airport Fuel Tax (litre) $: 0.00 Comments About Fees: Fuel Prices 100LL $: 0.00 Mogas $: 0.00 Jet Fuel $: 0.00 Fuel Prices with Taxes 100LL $: 0.00 Mogas $: 0.00 Jet Fuel $: 0.00 Date of Fuel Prices Fuel Price Comments Fuel/Dealers *(include Telephone Numbers) No fuel available Airport Management Alberta Sustainable Development, Forest Protection Division & The MD of Wood Buffalo Tel:

6 6 2.2 Spring Reduction Factor (SRF) Due to the possibilities of fines in the sub-base course a Spring Reduction Factor (SRF) of 20% has been adopted to this layer. 2.3 CBR subsoil CBR Technology Inc. executed CBR tests of the subsoil dated July 16, 2011 (see attachment B). An average CBR value 10,2 and a standard deviation s = 1,9 was found. As a result a CBRsubsoil 8% shall be used for the runway bearing strength calculations. Summarized: - CBRsubsoil 8%. 2.4 Runway The runway structure consists from top to bottom of a seal coat (macadam) 25 mm thickness, a base course 250 mm thickness and a sub-base course 350 mm. The seal coat has a good condition. With reference to the Equivalent Granular Thickness t the runway surface seal coat ratio will be 2, the base course ratio will be 1 and the sub-base course ratio will be 0,8 (please see paragraph 2.2). As a result t = = 580 mm. Summarized: - Equivalent Granular Thickness t = 60 cm. Please note the painted markings on the gravel runway surface. This indicates a seal coat application in good condition. (Pictures courtesy of CBR Techn. Inc., Calgary)

7 7 3.0 CALCULATION. 3.1 Maximum allowable tire pressure For the assessment of the maximum allowable tire pressure the CBR value of the runway surface is applicable. The measured CBR value of the runway surface at the edges of the runway is CBRave = 38,5 and standard deviation s = 4,5. The CBR value to be used for calculation purposes is CBR 34. A runway surface with CBR 34 results in a maximum allowable tire pressure of 1,17 MPa (Mega Pascal) or 170 psi. - Maximum allowable tire pressure RW09-27 is 1,17 MPa (170 psi). Please note: With reference to the runway centre CBR 55 is applicable. That means a maximum allowable tire pressure of 1,90 MPa or 275 psi. However, the value at the edge of the runway is decisive. 3.2 Runway bearing strength PLR (Transport Canada practice) For the Pavement Load Rating (PLR; Transport Canada practice) the runway structure and the CBR value of the undisturbed subsoil/subgrade are applicable. With reference to paragraph 2.3 the calculations will be executed for CBRsubsoil 8% Runway bearing strength PLR The CBR value to be used is CBRsubsoil 8%. The indicated CBR value results in a Subgrade Bearing Strength (S value): S = 110 kn. The Equivalent Granular Thickness (please see paragraph 2.4) t = 60 cm. With reference to the above mentioned values (S = 110 kn and t = 60 cm) the calculation of the Pavement Load Rating (PLR) results in PLR 9. Summarized: - PLR 9 (1,17 MPa or 170 psi). 3.3 Runway bearing strength PCN (International practice; ICAO) With reference to paragraph 2.3 the calculations will be executed for CBRsubsoil 8%.

8 Runway bearing strength PCN The runway bearing strength PCN (International Practice; ICAO) for category B subgrade (CBRsubsoil 8-13) is related to and will be derived from the PLR value (PLR 9): - PLR 9 gives PCN = 41,3541 which results in: PCN 41. With reference to ICAO, Annex 14, Aerodromes, the ACN-PCN method also presents the Pavement Type (Rigid or Flexible), the subgrade strength category (A to D), the maximum tire pressure category (W to Z) and the evaluation method (Technical evaluation or Using aircraft experience). Please see attachment A. With reference to Leismer Airport (CET2): - The Pavement Type is F (flexible); - The subgrade strength category is B (Medium: CBRsubsoil 8-13); - The maximum tire pressure category is medium (please see paragraph 3.1 and attachment A); - Evaluation method is T (technical evaluation). 3.4 Check up on calculated PLR and PCN The applicable computer programs used: - Transport Canada (TC) computer program Aircraft Load Rating (ALR) ; - Transport Canada (TC) computer program Flexible Pavement Aircraft Classification Number (ACN) ; - COMFAA 2.0 (FAA) Computer Program for ACN Calculation Aircraft data At Leismer Airport the critical aircraft types are assumed to be the BAe146 types 100, 200 and 300. The decisive aircraft will be BAe : - Maximum Operating Weight: 462,7 kn; - Minimum Operating Weight: 230,0 kn; - Wheel Configuration: dual Main Gears; - Percent Load on one Main Gear: 47,1 %; - Tire pressure: 1,08 MPa; - Wheel Coordinates of the Main Gear: 1. x = 0 and y = 0; 2. x = 0 and y = 71,0 cm ALR calculation (TC) By using the computer program the calculated Aircraft Load Rating (ALR) must be equal or lower than the PLR value as calculated in paragraph For Leismer Airport it is PLR 9. With reference to the computer program calculation the ALR of the critical aircraft is ALR 8,07 (please see page 9).

9 9 Transport Canada (TC), ALR calculation AIRCRAFT LOAD RATING (ALR) AIRCRAFT LOADING CHARACTERISTICS Aircraft Name : BAe Percent Load on Gear : 47,1 Tire Pressure (MPa) : 1,08 Wheel Coordinates (cm): Wheel # X Y PAVEMENT DESIGN THICKNESS 1 0,0 0,0 2 0,0 71,0 Operating Flexible t(cm) for S(kN) of Rigid h(cm) for K(MPa/m) of Weight (kn) ,7 98,19 59,82 35,94 17,08 27,78 26,10 24,28 22,51 230,0 59,02 30,17 15,38 3,27 19,11 17,91 16,66 15,45 AIRCRAFT LOAD RATING Operating Nominal Flexible ALR for S(kN) of Rigid ALR for K(MPa/m) of Weight (kn) ALR ,7 8,30 7,71 7,97 8, ,90 8,07 8,22 8,30 230,0 5,63 5,23 5, ,28 5,26 5,18 5,18 With reference to S = 110 kn: - Required runway structure thickness t = 0,5 x (59,82 35,94) + 35,94 = 47,88 cm; - Calculated ALR = 0,5 x (8,17 7,97) + 7,97 = 8,07 Conclusion: - The runway structure of Leismer Airport (t= 60 cm) is sufficient for the BAe ; - The bearing strength of RW09-27 of Leismer Airport (PLR 9) is sufficient for the BAe

10 ACN calculation (TC) By using the computer program the calculated Aircraft Classification Number (ACN) must be equal or lower than the PCN value as calculated in paragraph For Leismer Airport it is PCN 41. With reference to the computer program calculation the ACN of the critical aircraft is ACN 26 (see calculation below). Transport Canada (TC), ACN calculation Aircraft Name: BAe Aircraft Mass (kg): Tire Pressure (kpa): 1080,0 Percent Load on Gear: 47,0 Alpha Value: 0,9 Grid Location: X = 0,0 cm Y = 0,0 cm Grid Increment : X = 0,00 cm Y = 3,94 cm Number of Grid Lines: X = 10 Y = 10 Wheel Coordinates(cm): Wheel # X Y 1 0,00 0,00 2 0,00 71,00 ESWL (kg) CBR (PASSES 10000) T - DEPTH (cm) ,56 0, ,00 94,13 The ACN for a subgrade CBR of 3 is 31,63 ESWL (kg) CBR (PASSES 10000) T - DEPTH (cm) ,56 0, ,00 61,27 The ACN for a subgrade CBR of 6 is 28,05 ESWL (kg) CBR (PASSES 10000) T - DEPTH (cm) ,56 0, ,00 43,17 The ACN for a subgrade CBR of 10 is 24,74 ESWL (kg) CBR (PASSES 10000) T - DEPTH (cm) ,56 0, ,00 33,35 The ACN for a subgrade CBR of 15 is 24,15

11 11 With reference to CBR 8%: - Calculated ACN = 0,5 x (28,05 24,74) + 24,74 = 26,395 Conclusion: - The bearing strength of RW09-27 of Leismer Airport (PCN 41) is sufficient for the BAe ACN calculation (FAA) A double check has been executed by means of the ACN calculation computer program of the FAA. With reference to this program the calculated ACN is 25 (please see print below and page 12).

12 12 FAA COMFAA 2.0, ACN calculation (Ground Flotation Program Results, English Units) BAe 146 Number of wheels = 2 X (lateral) coordinates of wheels: -13,98 13,98 Y (longitudinal) coordinates of wheels: 0,00 0,00 No. of grid points (X, Y) = 9 9 Grid origin (X, Y) = -13,98 0,00 Grid increments (X, Y) = 1,75 0,00 Number of sets of mass and tire pressure = 1 Aircraft Mass (kg, lb) = , Tire Pressures: 127,63 127,63 Percent Mass on Main Gear = 94,20 Number of Main Gears = 2 Load on One Tire (kg, lb) = , Tire Contact Radii: 7,59 7,59 Coverages for ACN = Alpha Value for Gear = 0,9000 ESWL, kg CBR DEPTH, cm ACN ,00 91,85 30, ,00 59,47 26, ,00 41,65 23, ,00 31,52 21,57 ESWL, lb CBR DEPTH, in ACN ,00 36,16 30, ,00 23,41 26, ,00 16,40 23, ,00 12,41 21,57 With reference to CBR 8%: - Required runway structure thickness t = 0,5 x (59,47 41,65) + 41,65 = 60,56 cm; - Calculated ACN = 0,5 x (26,43 23,04) + 23,04 = 24,735 Conclusion: - The runway structure of Leismer Airport (t= 60 cm) is sufficient for the BAe ; - The bearing strength of RW09-27 of Leismer Airport (PCN 41) is sufficient for the BAe Please note: The differences between the calculation results of the mentioned computer programs are marginal. Due to the fact that the COMFAA 2.0 program from the FAA does not allow adaptation of the tire pressure the TC program is considered to be decisive.

13 PRESENTATION. 4.1 Transport Canada presentation Presentation corresponding the ALR/PLR-system as directed by Transport Canada (TC). With reference to the calculation as mentioned before the following presentation is applicable. PLR 9 (1,17 MPa or 170 psi) gravel runway with seal coat 4.2 International (ICAO) presentation Presentation corresponding the ACN/PCN-system as standardized by the International Civil Aviation Organization (ICAO). With reference to the calculation as mentioned before the following presentation is applicable. PCN 41 / F / B / 1,17 MPa / T gravel runway with seal coat Note: With reference to the codes please see attachment A.

14 SUMMARY Leismer Airport (CET2): - Gravel runway with a seal coat (macadam) and a structure thickness t = 62,5 cm (Equivalent Granular Thickness t = 60 cm); - Runway surface strength is CBR 34%: the maximum allowable tire pressure is 1,17 MPa (170 psi); - Subgrade or subsoil strength is CBR 8%; - Runway bearing strength is PLR 9 (TC-practice) and PCN 41 (International ICAO-practice); - Aircraft types BAe , -200 and -300, the BAe is decisive; - BAe maximum tire pressure is 1,08 MPa (157 psi), aircraft load rating is ALR 8, aircraft classification number is ACN 26. Conclusion: - With reference to the bearing strength and maximum tire pressure RW09-27 of Leismer Airport can be used by all BAe146 type aircraft (Standard Tires, All Speeds) without any restriction or limitation.

15 15 Runway bearing strength (PLR): LEISMER AIRPORT (CET2) (Pavement Load Rating PLR; Transport Canada practice) PLR 9 (1,17 MPa or 170 psi) gravel RW with seal coat Note: RW09-27, gravel surface with seal coat (macadam). Legend: PLR 9: All aircraft with ALR 9 or less may operate on RW09-27 without weight limitation; 1,17 MPa or 170 psi: Maximum allowable tire pressure. October 2011.

16 16 Runway bearing strength (PCN): LEISMER AIRPORT (CET2) (Pavement Classification Number PCN; International practice, ICAO) PCN 41 / F / B / 1,17 MPa / T gravel RW with seal coat Note: RW09-27, gravel surface with seal coat (macadam). Legend: PCN 41: All aircraft with ACN 41 or less may operate on RW09-27 without weight limitation; F: Flexible runway structure (gravel); B: Subgrade strength category Medium (CBR8); 1,17 MPa: Maximum allowable tire pressure; T: Technical evaluation (representing a special study). October 2011.

17 17 Attachment A

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19 19 CBR test results as measured by CBR Technology Inc. by means of the Boeing High Load Penetrometer. Attachment B Leismer Airfield, July 16, 2011.

20 20 Attachment C BAe specification.

21 21