# AC 20-123: Avoiding or Minimizing Encounters with Aircraft Equipped with Depleted Uranium Balance Weights During Accident Investigations - Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it) - Status: Current - Approved: December 20, 1984 - Last reviewed: June 6, 2024 - Family: AC 20-123 - 14 CFR parts: 135, 13 - Pages: 2 - PDF: https://openairdocs.org/files/sha256/79/16/7916960d6fe043d8c18ea81462d221f17b54bac2e249a6a257cc2c439cb14a9e - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/FED21DA1A772D8D9862569AF006AADBF.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ac/20-123 ## Versions - [AC 20-123](https://openairdocs.org/ac/20-123) (Current), approved Dec 20, 1984, 2 pages ## Text Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 e U.S. Deportment of TfonspoMW Fe&ml Aviu?&n + AdfnhWmti0n Advisory Circular Subject: AVOIDING OR MINIMIZING ENCOUNTERS Date: 12/20/84 ACNo: 20423 WITH AIRCRAFT EQUIPPED WITH Initiated by: ~\*('s-330 chrurge: **DEPLETEDURANIUMBALANCEWEIGHTS** DURING ACCIDBQ INVESTIGATIONS 1 PURPOSE. This advisory circular provides information and guidance to individuals who come in contact with depleted uraniun contained in aircraft control surfaces during accident investigations. 2 RELATED RIZADING MATERIAL,. Additional information on depleted uranium miy be found in the maintenance manual of each affected aircraft and also in’ service information provided by the aircraft manufacturer. 3 0 DISCUSSION. For many years, uranium to balance ailerons, aircraft manufacturers have used “depleted” rudders, and elevators on certain jet aircraft and rotor blades on certain helicopters. Uranium is 1 l/2 times as dense as lead and is the heaviest naturally occurring metal. According to a 1983 McI>onnell Dowlas Customer Service First Quarter publication, only "depleted" uranic is used, which means it has been processed to remove most of its uranium 235, the most highly radioactive form used in nuclear powerplants. The remaining uranium 238 e-nits only low-level alpha radiation. While the depleted uranium normally poses no danger, it is to be handled with caution. The main hazard associated with depleted uranium is the harmful effect the material could have if it enters the body. If particles are inhaled or digested, they can be chaTlically toxic and c&se a significant and longlasting irradiation of internal tissue, Depleted uranium is slightly d radioactive. To minimize radiation hazards, depleted uraniLvn balance weights are 100 percent cadmium plated during the manufacturing process. If the cadmium plating is intact, normal handling of the parts is considered to be nonhazardous and no special precautions are recommended. The use of radioactive materials in many every day applications is not at all unusual. tritium, a radioactive form of hydrogen, For example, is used in self-luminous signs, such as exit signs, and watches. Thorim, kich has a radiation activity level comparable to depleted uranium, is used in making gas mantels for lanterns, electronic equipllent, and high-quality optical lenses for cameras and overhead projectors. Also, smoke detectors contain americium 241, a radioactive material. 4 l PRECAUTIONS. a. Avoid contact with balance weights using depleted uranium. ch arrival at accident scenes of aircraft suspected of containing balance weights made of depleted uranium, determine if balance wights have been damaged or lost their cadmium plating coating. Request specialized assistance if balance weights have been damag.ed or lost their cadmium plating. No penetration of the - plating is allowed. ### Page 2 b Avoid breathing ox- swallowing particles of balance weights found damaged OI- w&h cadmiurrt plating damaged or lost l c. If it becomes necessary to handle balance weiqhts, the following precautions should be observed: (1) Personnel handling the balance wight should wear gloves. (2) Industrial eye protection should be wOrn. (3) Respirators rusk should k~ worn to ensure no radioactive dust particle ingest ion. d Gloves, wrapping material, wiping cloths, respirator filters, or any other'articles used in the handling of damaged balance weights should be discarded and appro;?x-iately labeled as radioactive waste and disposed of accordingly. Director of Airworthiness Par 4 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.