FAA and Scale OEM Requirements for Aircraft Weighing Scales

As a scale manufacture, Jackson Aircraft Weighing Systems follows the standard requirements for meeting FAA, EASA, CAA, DoT as well as many other regulatory bodies. Below are some details to help guide you in using, buying, or renting aircraft weighing equipment.

1. Introduction

Accurate determination of an aircraft's weight and balance is a fundamental prerequisite for ensuring the safety and efficiency of flight operations.¹ Operating an aircraft outside its certified weight and balance envelope can severely compromise its performance and handling characteristics. Immediate safety concerns, adherence to weight and balance limitations is also a matter of regulatory compliance, as the Federal Aviation Administration (FAA) has established a comprehensive framework of regulations and guidelines to govern aircraft operations within these critical parameters.

These regulations, found in various parts of Title 14 of the Code of Federal Regulations (CFR), including Parts 91, 121, 125, and 135, set forth the mandatory requirements for aircraft operation and maintenance concerning weight and balance. Advisory Circulars (ACs) and handbooks issued by the FAA provide detailed guidance and recommended practices for meeting these regulatory obligations. Jackson Aircraft Weighing Systems will provide a comprehensive overview of the FAA requirements for aircraft weighing scales, covering approved scale types, accuracy and calibration standards, relevant FAA documentation, and specific considerations for different categories of aircraft. It serves as a reference for aviation professionals involved in aircraft maintenance, safety inspections, and regulatory compliance.

2. Regulatory Framework: FAA Documents Governing Aircraft Weighing

2.1 Advisory Circular AC 120-27F FAA Advisory Circular AC 120-27F - Aircraft Weight and Balance Control

This advisory circular (AC) provides operators with guidance on how to develop and receive approval for a Weight and Balance (W&B) control program for aircraft operated under Title 14 of the Code of Federal Regulations (14 CFR) part 91 subpart K (part 91K), and parts 121, 125, and 135. This AC presents recommendations for an acceptable means, but not the only means, to develop and receive approval for a W&B control program, and includes guidance for using average and estimated weights in accordance with part 121, § 121.153(b) and other applicable sections of parts 91K, 121, 125, and 135.

• The certificate holder or user shall establish and follow instructions for weighing the aircraft that are consistent with the recommendations of the aircraft manufacturer and scale manufacturer.
• The scale user shall ensure that all scales are certified and calibrated by the manufacturer, returning the scale to the manufacture is always the best choice for calibrations.
• If a certified laboratory is to be used, that laboratory must have been trained and certified by the scale manufacture to conduct calibrations on that particular type of equipment.
• Department of weights and measures calibrations should be avoided as they are generic and will not have the manufacture training to conduct a proper calibration.
• The operator may calibrate the scale under an approved calibration program as long as the operator has the proper calibration test stand, correct master standard installed and calibrated with NIST traceable certification, has been trained and certified by the scale manufacture in the proper technic and method to calibrate the specific scale type.
• The user shall also ensure that the scale is calibrated within the manufacturer’s recommended time, or time periods, as specified in the operator’s approved calibration program.
• Deviation's from the manufactures recommended time can only be conducted if the certificate holder has short term, long term, and or sample time extension capability in their Operations Specifications under their approved calibration program.

2.2 FAA Aircraft Weight and Balance Handbook (FAA-H-8083-1B)FAA Aircraft Weight and Balance Handbook

The Aircraft Weight and Balance Handbook (FAA-H-8083-1B) was produced by the Federal Aviation Administration (FAA) with the assistance of Safety Research Corporation of America (SRCA). The FAA wishes to acknowledge the following contributor: Larry Jackson of Jackson Aircraft Weighing Service, for content and photographs used in Chapter 3

2.3 Title 14 of the CFR (Parts 91, 121, 125, 135, 43)Title 14 of the Code of Federal Regulations (eCFR)

The link above will take you directly to Title 14, from there you can find the parts.

2.4 Manufacturer's Data

Jackson Aircraft Weighing Systems is a manufacture of scales for aviation use. As such, we use a standard accuracy requirement: All scales shall be calibrated and accurate to 1/10th of 1% or (3) three indicator divisions which ever is greatest. Some manufactures will have different statements of accuracy for their equipment, check with different manufactures for their accuracy statements.

3. Types of Aircraft Weighing Scales

3.1 Platform Scales (Ramp Wheel Scales)

Platform scales are scales that sit on the ground, using ramps or direct jacking method, place the aircraft tires in the center of the platform, read the weights and remove the aircraft from the scales. Platforms are useful for small shops that may not have enough jacks or types of jacks needed to weigh many aircraft. Non retractable type of aircraft will for the most part always use platform type scales as the aircraft does not have jacking points for top of jack load cell use.

3.2 Top of Jack Load Cell Scales or commonly called Jack Top Cells

Top of Jack kits are available in 10K, 25K 50K and 100K kits

Load cells commonly referred to as "Top of Jack Load Cells" are transducers that mount on top of regular aircraft jacks. Not all aircraft jacks will have mounting provisions for these cells, in that case jack adapters must be installed and used to mount the cells properly. There are two types of Jack Adapters:

One is called an "Over the Top" jack adapter, this adapter fits over the top of your aircraft jack ram. Check your jack ram diameter for between 1.5 inches to 2.75 inches.

One is called an "Insert jack adapter" this adapter fits into your jack ram after the manual adjustable ram tube or rod has been removed.

The "Insert jack adapter" this adapter fits into your jack ram after the manual adjustable ram tube or rod has been removed.

4. Accuracy and Calibration Standards for Aircraft Weighing Scales

As stated above, Jackson Aircraft Weighing Systems uses a standard accuracy statement: Aircraft scales, Platform or Top of Jack Load Cells, shall be calibrated to within 1/10 of 1% or three (3) indicator divisions, whichever is greater. What this means is that your scales maximum considered accuracy would be within this range, a 5,000 lb scale would be accurate with in +/- 5lbs (1/10th of 1%) since the scale reads in a 1lb count, the three indicator divisions would be the lessor of the two with 1/10th of 1% being the grater number. You can apply this to 25,000 lbs and 1/10th of 1% would be 25lbs, again not the division count as the % is the greater of the two.

Also as stated, some other competitors may use a different accuracy, their accuracy will deal with percentage as well but they may use a different application of load and weight.

What is the difference between regular industry scales and aircraft scales? Standard scales may be accurate to 1% and be considered as being accurate. Aircraft Scales must be within 1/10th of 1%, or 10 times more accurate, and that is what you are paying for. Don't be fooled by other scale companies, hold them to at minimum 1/10th of 1% and test your scales for accuracy.

What is the FAA accuracy rules on scales? Believe it or not, they do not have an accuracy standard! What they say in all the research is that the scale must be calibrated by the manufacture or a certified lab. We add to that: The lab must be trained and certified by the manufacture and have the proper test stand to conduct the work.

With the above being stated, it is important to know who you are buying an aircraft scale from, what you are buying is at minimum meeting the known standards for use in aviation, and the scale performs, repeating its numbers and providing good results.

5. General Procedures for Weighing Aircraft (FAA Recommended Practices)

For FAA recommended practices, refer to the above links to the hand book and or title 14.

6. Specific Considerations for Weighing Different Aircraft Types

Jackson Aircraft Weighing Systems builds scales for all the different ranges of aircraft types. Please consider, you would not use a 100ft lb torque wrench to torque a 10 inch pound tail rotor nut, so why would you want to buy a 50,000 lb per cell kit to weigh a small twin, it just is not the right tool for the job.

Jackson Aircraft Weighing Systems groups scales into 4 divisions:

0-10,000 lb aircraft weight, general aviation, helicopters, through light turboprops or light jets.

0-25,000 lb aircraft weight, small jets, through small corporate jets, including regional jets.

0-50,000 lb aircraft weight, large corporate jets, regional jets, single aisle jets.

0-100,000 lb aircraft weight, large airline jets.

7. Certification and Calibration Requirements in Detail

Certification in general must be traceable to the National Institute of Standards and Technology or N.I.S.T. This means that your scale Original Equipment Manufacture will guarantee their scales calibrations are traceable to NIST. There are levels of of traceability: Level 1: Directly traceable to NIST, This means that your standard cell used to calibrate your aircraft scale is only one level removed from NIST, your standard was calibrated by NIST. Level 2: Traceable to NIST, This means that your standard was calibrated by a directly traceable standard and that you are two levels removed from NIST. Level 3: Traceability is in question, or your lab is more than three times removed, This means your lab and or standard is now not at a level considered for aircraft scale calibration.

8. Commonly Used or Recommended Scale Brands and Models

There are only a few actual "aircraft scale" manufactures that dedicate a full production line to aircraft scales. Jackson Aircraft Weighing Systems has only one job, that is making the greatest aircraft weighing system in the world. Being a worldwide provider with customers world wide, our equipment is commonly used for anything form weighing helicopters in Europe to large airline jets in the Philippines.

Be careful, there are companies out there that sell scales as aircraft scales, these scales have been tested and found to actually be not of aircraft accuracy even though they were advertised as such. Some of these are Truck Scales, Race Car scales, and the notorious Bathroom scale. We see this all the time, companies that purchased the wrong type of scale and or the wrong manufacture, only to find out that the savings found, are quickly spent after buying

9. Conclusion

Jackson Aircraft Weighing Systems is a world wide company with full international sales and support. Our goal is to use the information found in the AC's, Handbooks, and Regulations, then condense it down to an easy understanding of the "What and How" in order to assist our customers with the information they need in purchasing, renting, using of aircraft weighing equipment and its use.

Jackson Aircraft Weighing Systems operates many different websites, these sites are informational for specific aircraft and or helicopter weighing and they have pictures and details for the proper weighing equipment we offer. Any where in the world, you can call us or email us with your needs and or problems in aircraft weighing that we can solve for you. Contact us today at 561-281-6179 or email us at sales@aircraftscales.com