Our responsibility is to give our customers both internal and externa - PDF document

1 ABSTRACT Our responsibility is to give o
ABSTRACT Our responsibility is to give our customers, both internal and external, what they need and expect from us. These expectations are often defined in the MIL Specs and SAWE RPs referenced in contracts. Several SAWE RPs have been adopted to replace MIL Specs (page 9). RPs spell out many customer expectations such as report formats, cost, performance and operational requirements, but one of the areas often overlooked is the accuracy of the actual mass properties measurements. Statements like “Actual weight obtained by measurement on an accurate scale or other weighing device” (RP15), Scales shall have an accuracy of at least 0.1 percent of applied load” (RP7D) and “Item measurements shall be performed in accordance with recommended industry procedures” (RP7D) are vague or incomplete. This proposed FRP is intended to provide clarity and consistency. This proposal is from the viewpoint of military fighter aircraft, but the intent is to develop on

2 e or more documents relevant to all of t
e or more documents relevant to all of the weight engineering fields. Of the documents listed in the References (page 7) most do not state accuracies for the measurements or instruments used for mass properties measurements. When a requirement is given it implies that aircraft scales are to be calibrated to an accuracy of no less than 0.1% of applied load. When trying to find the requirements for other measurements such as engines, stores and subassemblies little was available. Although methods and techniques play a large part in the accuracy and validity of any measurement they are not mentioned. Presumably this is left to the recommended industry procedures. The training and qualifications of those who perform the measurements is also generally left to chance. There is also very little information on other related subjects like linear and angular measurements, equipment sizing, operator expertise and training, or measurements methods and procedure

3 s. All of these can play a large part in
s. All of these can play a large part in the validity of the mass properties data we deliver to our customers. A list of questions involving aircraft weighing methods and requirements (page 10) was circulated to several aircraft manufacturers and operators. These questions indicate that there is a need for an understanding of the underlying measurement principles. OBJECTIVES The intension of this proposed FRP is To standardize the measurements that make up the products we deliver to our customers To provide a higher level of confidence in the data we depend on day-to-day. III.To establish a consistent and accepted methodology for making mass properties measurements. To define the requirements to be technically competent to perform weight and balance measurements. To set the expected accuracy capabilities of the equipment used to make various measurements that result in the data we deliver. The quality of measurement equipment and its calibration

4 can vary greatly from site to site as c
can vary greatly from site to site as can the experience of those measuring and reporting the data. Having an FRP that establishes these criteria would give the weights engineer better control; start to finish, over the deliverables he is held accountable for. These requirements would also be levied on all suppliers of hardware. A better understanding of how the actual weight data is obtained, and its validity, provides the engineering staff and the customer with a greater degree of confidence in that data. This FRP would contain the requirements that are common to all or most areas of weights engineering, making this information easily referenced and revised. This effort should include input from commercial aircraft, marine vessels, surface transportation and metrological experts, among others. I believe that, with the input of our membership, this type of document would prove valuable in our relations with our customers and would help “get us all

5 on the same page”. This FRP isn’t inten
on the same page”. This FRP isn’t intended to be a set of burdensome details. Rather a consensus of experts to insure the quality of the data and products we deliver to our customers. The SAWE should take the lead and define the “recommended industry procedures” to set the standards for equipment accuracy, measurement methods and operator qualification. T.O. 1-1B-50 Basic Technical Order for USAF Aircraft Weight and Balance – Dated 1 March 2005 Section 6-2.4 Calibration of Weighing Equipment “….. are responsible for ensuring that weighing equipment under their jurisdiction are calibrated periodically and certified by a government inspector of weights and measures or by a commercial scale officials in accordance with TO 00-20-14 and TO 33K-1-100.” NAVAIR 01-1B-50 and Balance Control – Dated 15 August 2003 Section 4-9 Personnel Qualification Requirements Military and civilian personnel must be qualified as follows: Section 4-9.2 “Personnel assign

6 ed responsibility for weighing aircraft
ed responsibility for weighing aircraft (i.e. individuals qualified to lead a weigh team as opposed to those in a supporting role) must be qualified by graduation from one of the FASO weight and balance classes, successful completion of the Society of Allied Weight Engineers aircraft weigh course or NAVAIRSYSCOM (AIR-4.1.5) accepted equivalent, plus have actual experience in weighing aircraft with active participation in a minimum of twenty aircraft weighings covering at least four different TMS aircraft, or six weighings of a specific TMS aircraft when the individual will be weighing only this TMS aircraft. Weighing experience must have been obtained within the previous year.” Section 6-2.4 Calibration of Weighing Equipment “All custodians of weighing equipment (scales) are responsible for having it calibrated and certified by a government inspector of weights and measures or by a commercial scale officials at least once every six months. All calibr

7 ations must be traceable to a National B
ations must be traceable to a National Bureau of Standards (NBS) standard. Calibration procedures shall be those provided by the scale manufacturer. Scales shall have an accuracy of at least 0.1 percent of applied load.” TM 55-1500-342-23 Army Aviation Maintenance Engineering Manual – Dated 29 August 1986 Section 3-2 Weighing Systems “To ensure accurate results in determining aircraft weight, the instructions provided in the technical manuals for the specified weighing system must be followed and the system must be calibrated. For calibration requirements see TB 43-180” MIL-W-3947B Weight and Balance Control System for Guided Missiles and Space Launch Vehicles – Dated 18 September 1991 Section 4.1 General “The Government Inspector shall certify to the correctness of vehicle actual mass properties determination. He shall insure that the measuring and testing equipment requirements of paragraph 3.4 of MIL-Q-9858, Quality Control System Requirements, a

8 re fulfilled.” Certification and Calibra
re fulfilled.” Certification and Calibration of Weighing Devices– M. Browne, SAWE paper #2443 Page 5 - Specification of Accuracy - “In a weigh scale application, errors are more properly expressed as: ± (percentage of applied load), or ± (a specified division), whichever is greater’ Is it acceptable to have usable fuel in the fuel tanks for weighing? Does fuel need to be sumped (drained) for weighing? Should the Hydraulic Fluid be full, empty, or partially full for weighing? Should the Engine Oil be full, empty, or partially full for weighing? Should the APU Oil be full, empty, or partially full for weighing? Should the Landing Gear Fluid be full, empty, or partially full for weighing? Should the Oxygen bottles be full, empty, or partially full for weighing? Should the Waste Tanks be full, empty, or partially full for weighing? Should the Potable Water Tanks be full, empty, or partially full for weighing? Should the Lav's be Serviced or Drained for

9 Weighing Should you do a check for wet (
Weighing Should you do a check for wet (isolation) blankets before weighing, and if so what are the most common positions for wet blankets. Should brake pads be checked on thickness before weighing? What setting is required for the Stabilizer Trim for Weighing? What setting is required for the Flaps and Slats for Weighing? What setting is required for the Ailerons, Rudders, Elevators, & Spoilers for Weighing? Does the airplane have to be weighed indoors? If "yes" to indoors, what about ventilation system? If "yes" to indoors, can the hanger doors be open? If "no" to indoors, under what conditions can an airplane be weighed outdoors (i.e. how much wind is allowable)? Can the Passenger and Cargo Doors be open for weighing? Can the cockpit windows be open for weighing? What airplane Longitudinal Attitude is acceptable for weighing? What airplane Lateral Attitude is acceptable for weighing? Does the airplane need to be Dry for we

10 ighing? Does the airplane need to be Cle
ighing? Does the airplane need to be Clean for weighing? Can Exterior lines be attached for weighing? Can the Inventory of the Aircraft be done Before or After the Weighing? How do you decide when an Aircraft is Complete Enough for weighing? How many scale readings are required for a weighing (one, two, or more)? Is rotating scales required for weighing? What is the scale tolerance for weighing? What is appropriate closure on Weight between consecutive scale readings? What is appropriate closure on CG between consecutive scale readings? Is it OK to weigh on platform scales? Is it OK to weigh on load cells under jack points on gear? Is it OK to weigh on load cells under primary jack points? Is it necessary to measure distances between Gear reaction points? What is required to handle non-vertical landing gear shock Struts? What is the acceptable temperature range for weighing? Do all scales read simultaneously, or can scales be read over a few minutes?