what is a pull test and saftey thong

A pull test is where the plane, lines and handle ready to fly are checked for safety by attaching a scale to the handle and pulling the control system up to a weight specified in the AMA rule book for a given displacement engine. A safety thong is attached to the handle and has a loop to go over the hand and around the wrist, this is to keep the model from escaping in case the pilot may trip and fall down or have a heart attack or any other reason he might lose his grip on the handle.

Underaged Pilot,
A pull test is a safety procedure intended to establish that your handle, lines, and bellcrank mount are strong enough to handle the flight loads. At a contest the pull test will be done with a scale, usually a modified fishing scale, hooked to the handle. One person holds the scale and the pilot holds his model and pulls on it up to the specified force. Most of us who have been around a while have had,or seen, a control system break during this test. The AMA rule book specifies the amount of pull for different competition events and different weights of models. Pull tests should be done with a smooth pull. Jerking or "twanging" the lines can cause a failure. BTW, rule books are free from AMA, just ask. Even if you don't have a scale, a good pull of about twice what you expect the model to do can make you feel better about the security of your system.

Saftey thongs are straps, mine are heavy duty boot laces, that connect the handle to your wrist. They prevent a flyaway if you let go of the handle.