What documents are required for weight and balance record-keeping on an aircraft?

At a minimum, aircraft weight and balance records must include the current empty weight, empty center of gravity, and a list of equipment included in that empty weight, all of which must be retained in the aircraft or made available to the pilot. These records are typically contained in the Aircraft Flight Manual (AFM) or a supplemental weight and balance report prepared after a major alteration or repair. Per 14 CFR Part 43 and Part 91, whenever an alteration or repair affects weight and balance, the maintenance record must be updated to reflect the new data.

Who is responsible for updating weight and balance records after maintenance or an alteration?

The aviation maintenance technician (AMT) or repair station performing the work is responsible for updating weight and balance data whenever a repair or alteration affects the aircraft's weight or center of gravity, as required by 14 CFR Part 43, Appendix B. The updated weight and balance report must be signed, dated, and include the AMT's certificate number. This revised documentation then becomes part of the permanent aircraft records and must accompany the aircraft.

Where must weight and balance records be kept, and how long must they be retained?

Current weight and balance data must be kept in the aircraft at all times and made available to the pilot prior to flight, as outlined in 14 CFR Section 91.9 and the PHAK. Historical weight and balance records superseded by later weighing or alterations are generally retained by the aircraft owner or operator for at least one year, per 14 CFR Section 91.417(a)(2), while current weight and balance information must be retained for the life of the aircraft. Keeping thorough records ensures airworthiness continuity and supports safe loading decisions throughout the aircraft's service life.

Weight & Balance Record-Keeping & Documentation Requirements

Every aircraft that flies in the United States must have a current, accurate weight and balance record on board or immediately available. For aviation maintenance technicians (AMTs), this is not merely a paperwork formality — it is a legal obligation grounded in 14 CFR and a direct safety responsibility. An aircraft whose weight and balance data is outdated or incorrect may be operated outside its certified envelope without anyone knowing it, with potentially catastrophic results. Understanding what documents are required, when they must be updated, and how they must be maintained is therefore a core AMT competency.

This article walks through the regulatory framework, the types of records involved, the conditions that trigger updates, and the practical steps an AMT must follow to keep weight and balance documentation compliant and accurate.

The Regulatory Foundation

The primary regulatory authority for weight and balance record-keeping comes from 14 CFR Part 43 (Maintenance, Preventive Maintenance, Rebuilding, and Alteration) and 14 CFR Part 91 (General Operating and Flight Rules). Part 43 requires that a maintenance record entry be made any time maintenance, preventive maintenance, rebuilding, or alteration is performed. When that work affects the aircraft's weight or center of gravity (CG), the weight and balance records must be revised accordingly.

14 CFR 91.103 requires that before beginning a flight, the pilot in command become familiar with all available information concerning that flight, which includes ensuring the aircraft is loaded within its approved weight and balance limitations as specified in the aircraft's flight manual or other approved documentation. Part 91.417 mandates that the aircraft owner or operator retain maintenance records, including weight and balance records, for specific periods. These records must be made available to the FAA upon request. Taken together, these regulations create a clear chain of responsibility: the mechanic who does the work must make the proper entry, and the owner/operator must keep it.

Core Weight and Balance Documents

Several distinct documents make up a complete weight and balance package. AMTs need to be familiar with each.

The Weight and Balance Report

The weight and balance report (sometimes called the weighing record or weight and balance data sheet) is the foundational document. It records the actual measured weight of the aircraft at the time it was weighed, the reference datum used, the weight at each weighing point, the empty weight, the empty-weight CG location, and the moment. This document is produced every time the aircraft is officially weighed. It must be signed by the person who performed the weighing and must clearly identify the aircraft by make, model, and serial number, as well as the registration number (N-number).

The Equipment List

The equipment list accompanies the weight and balance report and identifies every item of equipment installed on the aircraft at the time of weighing — and whether each item was included in the weighed empty weight or not. Items that are part of the empty weight are noted as installed; optional equipment that may be removed is listed separately. When equipment is added or removed from the aircraft, the equipment list must be updated to reflect the change. This is one of the most common record-keeping tasks an AMT performs in connection with weight and balance.

The Aircraft Flight Manual or Pilot's Operating Handbook

The Aircraft Flight Manual (AFM) or Pilot's Operating Handbook (POH) contains an approved weight and balance section that includes loading charts, moment tables, CG envelope graphs, and the original empty weight data for the aircraft as delivered from the factory. This document is FAA-approved for type-certificated aircraft and must remain in the aircraft at all times during flight per 14 CFR 91.9 and 91.203. The weight and balance section in the AFM/POH must be kept current. When the actual empty weight or CG changes due to maintenance or alteration, a revised weight and balance page or supplement must be inserted into the AFM/POH to reflect the current condition of the aircraft.

When Records Must Be Updated

AMTs must recognize the specific circumstances that require a weight and balance record update. Not every maintenance task affects weight and CG, but many do, and the determination of whether an update is required is the technician's professional responsibility.

Addition of equipment: Any time a new avionics unit, antenna, seat, cargo liner, supplemental oxygen system, or other item is permanently installed, the item's weight and its arm (distance from the datum) must be used to calculate the change in empty weight and empty-weight CG. The records must then be updated with the new empty weight and CG.
Removal of equipment: Similarly, removing installed equipment — even something as small as an interior panel or a redundant radio — changes the empty weight and may shift the CG. The records must reflect this.
Major alterations: A major alteration as defined in 14 CFR Part 43, Appendix A, such as the installation of a supplemental fuel tank, conversion of an engine, or structural modification, almost always requires a new or revised weight and balance report. Many major alterations also require a Supplemental Type Certificate (STC), which will carry its own weight and balance revision instructions.
Repairs affecting weight: Large structural repairs involving added material — such as patches, doublers, or replacement components heavier than the original — can measurably change the aircraft's empty weight. If the change is significant, the records must be updated.
Reweighing: After certain periods of time or after cumulative changes make the existing records suspect, the aircraft should be physically reweighed and a new weight and balance report generated. While the regulations do not specify a mandatory reweighing interval for most general aviation aircraft, good practice and some operator manuals call for periodic reweighing.

How to Update Weight and Balance Records Without Reweighing

When a relatively simple change is made — such as adding a single avionics unit — it is not always necessary to physically reweigh the entire aircraft. Instead, the AMT may use the algebraic method to calculate the new empty weight and CG mathematically. The process involves determining the weight and arm of the item added or removed, computing its moment (weight × arm), and then algebraically adding or subtracting the weight and moment from the existing totals to arrive at the new empty weight and new empty-weight moment. The new CG is then the new total moment divided by the new total weight.

This calculated update must be recorded on a revised weight and balance data sheet, which is then placed in the aircraft records. The old data sheet is not destroyed — it is retained as part of the maintenance history. The AFM/POH weight and balance section must also be updated with the new figures, typically by inserting a revised page or an addendum signed by the AMT who performed the work.

Record Retention Requirements

Under 14 CFR 91.417, the owner or operator must retain weight and balance records for as long as the aircraft is operated. Specifically, current weight and balance information must always be available — it is considered a record that must be kept indefinitely because it reflects the aircraft's present condition. Records of maintenance, preventive maintenance, and alterations other than the records of the last annual/100-hour/progressive inspections and total time in service must be retained for at least one year under 91.417(a)(2). As applied to weight and balance documentation, once a weight and balance report or equipment list has been superseded by a new weighing or a revision, the prior version should be retained at least this long, though many operators and shops keep superseded weight and balance data indefinitely as part of the aircraft's complete history.

For air carrier and commercial operators under Parts 121 and 135, retention requirements are more stringent and are specified in their operations specifications. AMTs working in those environments must be familiar with the additional documentation requirements imposed by those regulations and the operator's maintenance program.

Where Records Must Be Kept

The current weight and balance report and equipment list are generally required to be kept in or with the aircraft. While the regulations state that maintenance records may be kept at the principal maintenance base, the weight and balance data that reflects the current state of the aircraft is considered operational documentation that must travel with the aircraft so that pilots can perform valid preflight weight and balance calculations. Many operators keep a copy of the current data in the AFM/POH, which is required to be aboard the aircraft during all flights.

Key Numbers and Rules

Current weight and balance records must be retained for the life of the aircraft (as long as it is operated).
Records of maintenance, preventive maintenance, and alterations — including superseded weight and balance data — are generally retained for a minimum of one year per 14 CFR 91.417(a)(2).
Any maintenance entry in the logbook that involves a weight change must reference the revised weight and balance data or include the data in the entry itself.
The datum (reference point for all arm measurements) is established by the manufacturer and must be consistently used across all calculations and records.
A major alteration requires a Form 337 (Major Repair and Alteration form); the weight and balance revision associated with that alteration must be attached to or referenced on the Form 337.
The equipment list must be updated every time equipment is added to or removed from the aircraft, regardless of the weight impact.

Common Test Traps

Confusing the retention periods: The FAA knowledge test may ask whether weight and balance records must be kept for one year or for the life of the aircraft. Remember: current records are kept for the life of the aircraft; superseded records of maintenance and alterations are generally retained for at least one year under 91.417(a)(2).
Forgetting the equipment list: Many test questions focus only on the weight and balance report while ignoring that the equipment list is an equally required and equally perishable document that must be updated when equipment changes.
Assuming only major work triggers updates: Even relatively minor additions or removals — a small avionics unit, a new headset hook — must be reflected in the equipment list and, if the weight is significant, in the weight and balance data.
Mixing up who keeps the records: The owner/operator is responsible for record retention; the AMT is responsible for creating the proper entry. The AMT's obligation does not end when the work is done — the entry must be complete, accurate, and signed.
Overlooking the Form 337 connection: For major alterations, students sometimes forget that the weight and balance revision is an attachment to the Form 337, and that a copy of the Form 337 must remain with the aircraft's permanent records.

Weight and Balance Record-Keeping and Documentation Requirements