Staff Instruction. Ferry Fuel System Field Acceptance Criteria

Transcription

1 Staff Instruction Subject: Ferry Fuel System Field Acceptance Criteria Issuing Office: Civil Aviation Activity Area: Qualifying Document No.: SI File No.: A U Issue No.: 01 RDIMS No.: V5 Effective Date: TABLE OF CONTENTS 1.0 INTRODUCTION Purpose Applicability Description of Changes REFERENCES AND REQUIREMENTS Reference Documents Cancelled Documents BACKGROUND CONDITIONS AND LIMITATIONS STRUCTURAL CONSIDERATIONS TANK LOCATION CONSIDERATIONS FUEL TANK DESIGN SYSTEM DESIGN AND PERFORMANCE DOCUMENTATION CONTACT OFFICE... 7

2 1.0 INTRODUCTION 1.1 Purpose The purpose of this Staff Instruction (SI) is to provide guidance to Civil Aviation Safety Inspectors (CASIs) for the review, inspection and acceptance of ferry fuel systems installed on aircraft prior to issuing a Flight Permit for the intended flight. 1.2 Applicability This document is applicable to Transport Canada Civil Aviation (TCCA) Headquarters and Regional personnel involved in the inspection and acceptance of aircraft ferry fuel systems. 1.3 Description of Changes Not applicable. 2.0 REFERENCES AND REQUIREMENTS 2.1 Reference Documents It is intended that the following reference materials be used in conjunction with this document: Part V, Subpart XXIII of the Canadian Aviation Regulations (CARs) Normal, Utility, Aerobatic and Commuter Category Aeroplanes; Chapter 527 of the Airworthiness Manual (AWM) Normal Category Rotorcraft; Standard 507 of the AWM Flight Authority and Certification of Noise Compliance; Federal Aviation Administration Advisory Circular (FAA AC) B, dated Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair; and FAA AC 20-53B, dated Protection of Aircraft Fuel Systems Against Fuel Vapor Ignition Caused by Lightning. 2.2 Cancelled Documents As of the effective date of this document, the following document is cancelled: Maintenance and Manufacturing Staff Instructions (MSI) No. 45, Rev 0, dated Ferry Fuel System - Field Acceptance Criteria. 3.0 BACKGROUND In the past, the review of ferry fuel systems was not conducted uniformly among the regions. Since these systems are installed for ferry flight conducted under a Flight Permit, they do not require Aircraft Certification approval. However, without comprehensive guidelines, CASIs have found it difficult to review and accept these systems. As a result, a joint Aircraft Maintenance and Manufacturing and Aircraft Certification working group was formed to draft this AC to provide comprehensive guidelines to assist CASIs in conducting review and inspections of ferry fuel system installations. 4.0 CONDITIONS AND LIMITATIONS (1) Validity of this SI is subject to the following conditions and limitations: Valid only for aircraft certified to Normal, Utility, or Aerobatic Non-Transport standards (Chapter 523 of the Airworthiness Manual (AWM) or Civil Air Regulation 3) and Normal Category rotorcraft standards (Chapter 527 of the AWM or Civil Air Regulation 6); Valid only for non-pressurized aircraft; of 7 SI Issue 01

3 (f) (g) (h) Ferry Fuel System Field Acceptance Criteria Valid only for non-direct feed ferry fuel systems i.e. the supplemental ferry fuel is used only to replenish the main aircraft tanks, and does not provide fuel directly to the powerplant; The ferry fuel tank(s) must be accessible to the flight crew in flight, OR be externally mounted i.e. belly tanks; Valid only for metallic tanks and structures; Valid only for ferry fuel systems that contain no internal electrical components such as internal pumps, quantity transducers, etc.; The flight permit Operating Limitations/Conditions should state that the flight permit is valid only until the aircraft reaches its final destination, at which point the ferry fuel system must be removed and the aircraft returned to its type-certified configuration prior to further flight (this is in addition to any Standardized Operating Conditions and Limitations found in Standard 507, Appendix D, Schedule 1 that may apply); and This SI is not written for cases in which a Ferry Fuel System is installed by a Supplemental Type Certificate (STC) or Limited Supplemental Type Certificate (LSTC). (2) If the ferry fuel system does not meet any of the above conditions or limitations, or if the CASI has any remaining questions as to the ferry fuel system s acceptability following review of the system, the CASI is advised to contact the Regional Aircraft Certification Engineer for assistance. 5.0 STRUCTURAL CONSIDERATIONS (1) Acceleration Loads: The extent of structural substantiation for the ferry fuel installation depends on the amount and location of the added fuel and the modifications required to accommodate the fuel tank installation. Evaluation by the installer of the tank attachment hardware and local structure should be sufficient for the purposes of a simple system. The installer shall substantiate that the tank attachment to the aircraft is capable of restraining the full weight of each tank, including fuel, pumps, pallets, etc. when subjected to the inertial loads specified in the original certification basis of the aircraft i.e. for normal category fixed wing certified to Civil Air Regulation 3b and Chapter 523 of the AWM: 9.0 g forward, 1.5 g sideward, 3 g upward; (2) for normal category rotorcraft certified to Civil Air Regulation 6b and Chapter 527 of the AWM pre- Amendment 27-25: 4.0 g forward, 2.0 g sideward, 1.5 g upward; (3) for normal category rotorcraft certified to Chapter 527 of the AWM pre-amendment 27-32: 16.0 g forward, 8.0 g sideward, 4.0 g upward; (4) for normal category rotorcraft certified to Chapter 527 of the AWM post-amendment 27-32: 16.0 g forward, 8.0 g sideward, 4.0 g upward, 1.5 g rearward. (5) Emergency Landing Dynamic Loads: The tank attachments need not be substantiated for emergency landing dynamic loads. (6) Floor Loading: The installer shall attest that the floor loading does not exceed the airframe design limitation for the location of the tank. Supplemental distribution methods may be used to distribute the load if necessary e.g. plywood. (7) Gross Weight Increase: An aeroplane gross weight increase of a maximum of 10% is allowed without the need for substantiation, except in the case of aircraft where a Special Overweight Ferry Flight Authorization is specifically stated in the Type Certificate e.g. the Cessna C-172. Note: This gross weight increase does not apply to rotorcraft of 7 SI Issue 01

4 6.0 TANK LOCATION CONSIDERATIONS (1) Weight and Balance: The installer shall prove that the weight/center of gravity (CG) envelope limitations are not exceeded for the intended flight. Fuel burn profiles from both the ferry tanks and the existing aircraft fuel system should be accounted for including the effects of fuel sloshing (particularly in long tanks partially full) and fuel burn scheduling (which tank burns first, second, etc.). For installations that involve gross weight increases, the weight/cg envelope for weights in excess of the certificated maximum gross weight should be established such that the envelope is a linear extrapolation of the certificated envelope. In particular, for aircraft which have sloping sections of the weight/cg envelope (normally the heavy weight, forward CG region for conventional tractor powerplant installations), the envelope at elevated weights should respect the slope of the weight/cg envelope to ensure adequate longitudinal control exists (particularly in flare during an emergency landing condition). (2) Cabin Area Drainage: An airframe fuel drainage path should be evident that will provide a safe path for any fuel leakage from the ferry system to flow to an external drain, and that will prevent pooling of any ferry fuel leakage in a normal flight attitude. If no drainage path is available, then the installer should provide an externally drained drip pan under the ferry fuel system. (3) Cabin Area Ventilation: It should be evident that the cabin area in which the ferry tank is installed is well ventilated. The installer should affirm that accumulation of fuel vapors near an ignition source is not possible. A placard or instruction shall be provided to the pilot indicating how, when and the period of time it is necessary to ventilate the cabin following fueling service. (4) Emergency Exit Access: The crew shall have access to a minimum of one exit on each side of the aircraft with the ferry fuel system installed. (5) Ignition Sources: The tank(s) and lines should be located as remote as reasonably possible from any ignition sources. 7.0 FUEL TANK DESIGN (1) Tank Construction: The tank should be of standard metal construction. Internal tank baffles may be provided by the installer if required for surge, CG or other considerations. (2) Pressure Test: The installer shall demonstrate that the tank has been tested to 3.5 pound per square inch (PSIG) pressure. (Caution this pressure test should be performed hydrostatically). (3) Fuel Filler: The fuel tank filler (inlet) may be located inside the fuselage and should be designed to prevent spillage during servicing. (4) Expansion Space: Minimum expansion space of 2% of tank capacity through appropriate tank design should be substantiated by the installer. It should not be possible to overfill this expansion space. (5) Sump Capacity: Minimum sump capacity of 1% of system capacity should be confirmed by the installer. This may be accomplished by locating the fuel outlet above the lowest level of the tank. (6) Tank Drain and Strainer Provision: Tank drain capability and fuel outlet strainers are not required. (7) Tank Access Panels: Tank access/inspection panels are not required. The filler inlet should provide for a limited inspection capability. 8.0 SYSTEM DESIGN AND PERFORMANCE (1) Fuel Lines: The installer shall ensure that the fuel lines are aircraft quality and rated conservatively for the intended flow rate and pressure. In no case should the fuel lines be smaller in diameter than the existing aircraft lines. The fuel lines should be installed in accordance with standard practices found in FAA AC B or the type certificate holder s recommendations. The lines must be installed so as to be protected from accidental damage by occupants or cargo of 7 SI Issue 01

5 (2) Vent System and Vent System Low Points: The vent lines should be routed so as to avoid any low points which may accumulate moisture and freeze thus blocking the line. The ferry tank vents should be tee d into the existing aircraft vent lines if possible. If this is not possible, the ferry tank vents should be routed overboard in a manner that ensures a positive pressure differential is maintained in the tank. (3) Fuel Pumps: Electrical and manual transfer pumps should be aircraft quality and installed in accordance with standard practices found in FAA AC B or the type certificate holder s recommendations. Considerations for sizing of the pumps must include hazards resulting from too rapid or too slow of a fuel transfer. (4) Provision for Ferry Fuel Shut-Off Valves: A means to shut off the ferry fuel transfer flow and isolate the ferry fuel tank must be provided, that is accessible to the crew in flight. This means may be a transfer pump that prevents flow when not active. (5) Check Valves: A check valve(s) should be installed on the fuel transfer line(s) to prevent the possibility of back-flow from the aircraft fuel tanks into the ferry fuel tank. (6) Bonding for Electrostatic Concerns: Adequate bonding for electrostatic discharge concerns must be demonstrated by the installer; AN-10 wire or its equivalent is typically used, or acceptable methods found in FAA AC B. The installer shall affirm that the installed ferry fuel system demonstrates resistance s below 1.0 ohm between all components and at system/airframe interfaces. If two or more components are grounded to the aircraft structure in series, both ends of the ground circuit must be grounded independently to the structure to ensure that loss of an intermediate bonding connection will not leave any component isolated from the ground. (7) Lightning Considerations: In order to minimize lightning vulnerability it is extremely desirable that the ferry fuel vents tee into the existing aircraft vent system. If the installer chooses to add an additional external vent for the ferry fuel system, a flame arrestor shall be used. See FAA AC 20-53B for guidance. (8) Ferry Fuel/Airframe Fuel System Interface: The ferry fuel should be transferred to the aircraft main or header tanks, and never directly fed to the powerplant. The design of the ferry fuel system in combination with the operating instructions shall prevent overfilling of the aircraft fuel tank(s). One common design means used to transfer ferry fuel is to tee into a main-engine airframe fuel line. Then, while the opposite main tank is used to feed the engine, the ferry fuel is back-fed through the tee d interface into the main tank. (9) Tank Quantity Indication and Monitoring: If required for the fuel management procedure, a means for the crew to adequately monitor remaining ferry fuel quantity must be provided by the installer. For very simple ferry fuel systems where the full ferry quantity is transferred to the mains in one action, quantity indication is not required. However, in all systems a means must be provided for the crew to determine that the full ferry fuel quantity has been transferred. This means may be through a quantity indication, through monitoring of pump cavitation, or through other visual means. A method of determining the fuel quantity in each tank prior to flight should be provided. (10) Tank Quantity Measurement and Calibration: Measurement of the capacity of the ferry tank is normally established by the installer during the hydrostatic pressure testing. Calibration of ferry fuel quantity indication systems (if provided) is not required for simple ferry tank shapes e.g. simple cubic or rectangular shapes. (11) System Functional Test: The installer shall verify that a full functional ground test of the installed ferry fuel system has been performed, as well as substantiate that a limited demonstration of proper system function in flight has been performed. More complex ferry fuel systems may require more substantial flight-testing at the discretion of the installer and/or Inspector. (12) Engine Oil Capacity: The installer should provide proof that sufficient oil capacity is available for the duration of the ferry flight, considering the maximum expected oil consumption of 7 SI Issue 01

6 9.0 DOCUMENTATION (1) Required Documentation: The Inspector should confirm that the following minimum documentation has been provided by the ferry fuel system installer and is carried on board the aircraft: System Installation Instructions; System Operating Instructions; System Removal Instructions; and Ferry Limitations. (2) System Operating Instructions and Ferry Limitations may be provided in the form of either cockpit placards, or printed crew instructions. (3) Minimum Provision of Placards: The ferry fuel tank must be placarded to indicate type and quantity of fuel. The cabin/cockpit will be placarded No Smoking. (4) Operating instructions: Operating instructions must be provided by the installer for the use of the crew in flight, and must contain the following information: (f) Fuel Management Procedure that advises the crew as to proper operation of the ferry fuel and ferry fuel transfer system; Emergency Procedures required in the event of a failure of the ferry fuel system; information regarding the type and quantity of ferry fuel; instructions for tank filling; instructions to the crew, to the effect that, Every attempt should be made to consume the ferry fuel as soon as possible ; and instructions to the crew that the ferry fuel transfer system be operated in level flight only. (5) Ferry Limitations: Limitations due to the ferry fuel installation must be provided to the crew. These additional limitations may include: (f) (g) revised maximum take-off weights and CG limit computations; requirement for ventilation of cabin following fueling; the requirement for an airframe inspection in the event of an emergency over-weight landing; information to the crew to the effect that, This aircraft is operating with a ferry fuel installation which may affect the performance and limitations of the basic aircraft ; instruction that the aircraft must be returned to its original certification configuration and inspected following removal of the ferry fuel system; instruction to the crew to avoid severe turbulence, and if encountered, that the aircraft should be inspected for damage; and fuel loading limitations, if applicable, to ensure that the main fuel tank(s) and ferry fuel tank(s) are loaded in the proper sequence to prevent tipping of the aircraft of 7 SI Issue 01

7 10.0 CONTACT OFFICE For more information, please contact the: Chief, Standards and Procedures (AARTM) Phone: Fax: Suggestions for amendment to this document are invited, and should be submitted via the Transport Canada Civil Aviation Issues Reporting System (CAIRS) at the following Internet address: or by at: Original signed by Don Sherritt D. B. Sherritt Director, Standards Civil Aviation of 7 SI Issue 01