AD&D insurance pays only pays benefits in case of death or dismemberment as the proven and direct result of an (unintentional) accident, and it must happen within a certain timeframe (usually a couple of months). Accidents due to natural causes (illness, heart attack, …) or intentional causes (suicide) are therefore not covered.
When a covered accident results in death, normally the face value of the AD&D policy will be paid out. Dismemberment due to a covered accident pays out fractionally the policy face value. The loss of one member (like a hand, foot, hearing, eyesight, speech) could e.g. result in a payout of 50% of the benefits, the loss of more than one member would result in the payment of the full benefits. Partial or complete paralysis because of an unintentional accident normally pays out 25% to 50% of the benefits.
Typical exclusions (reasons not to pay out) are :