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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. 
AC 20423 12/20/84 

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