Confined Space Warning
Before building or maintenance starts, this article is essential reading.
DANGER: The Aft Compartment in a Seawind is a Confined Space!
Arnie Tanzman passed away on December 13, 2001 in Stateline, Nevada, while working inside the aft tail cone of his Seawind N711AT. He was in the process of changing out the Mallory fuel boost pump, which had seized after about 200 hours airtime service. He was overcome by the fumes of avgas displacing breathable oxygen.
Then, in 2007 my good friend George Osborne died the same way!
Two Seawind owners (that we know of) have died because of the confined space in the aft compartment of the Seawind. Following these tragic deaths, and since it is necessary to spend hours and hours in the tail cone a Seawind during building and/or maintenance, it is appropriate to make some information available about this little known deadly hazard. The terms "Oxygen Deficient Atmosphere," and more recently "Confined Space," are used synonymously.
To the surprise of most people hearing about it for the first time, death in an oxygen-deficient atmosphere or confined space is almost instantaneous. It occurs after just one or two breaths! By the time a person comprehends that they are in trouble, it is too late.
Oxygen-deficient atmospheres occur from many causes, but most often because the air in an enclosed space is displaced by another gas. This can occur with even non-toxic, inert gases. In the case of the two Seawind deaths, the oxygen was displaced by fuel vapors after a fitting in the fuel system was loosened.
Often times, like in the Seawind, the space doesn't even have to be very enclosed. In some cases, where there are heavy gases present (like argon and some other welding gases) they can displace and deplete the oxygen at the floor level of a large room. Likewise, lighter than air gases can create oxygen-deficient atmospheres in the top of some spaces.
The photo at the top of this chapter shows Chris from Planemakers working in the aft compartment of my Seawind N66SW. This photo illustrates the confined space in the aft compartment of a Seawind. Note also that the sides of the Seawind create a tub like space that will trap and hold heavier than air gases in the area that is lower than the sides.
During the mid 70's, while working in the Nuclear industry, we had extensive safety programs concerning this sinister hazard. One of the incidents that was used as an example is the following. (Please note, this story is being related from memory, some details may be missing):
During the 1970s, many of the dairy farmers and cattlemen were installing large ground-level tanks in which they would liquefy manure so that it could be easily pumped and handled for fertilizer. At one such installation, during the start-up process of the new facility, a farmer entered the tank and did not come out. His hired man, becoming concerned, went in to see if something was wrong. He didn't come out either.
After the men had been missing for a time, a concerned wife of one of the men called the sheriff, who then went out to investigate. The sheriff also entered the tank and didn't return.
Finally, one of the observers figured out that the tank was probably filled with methane gas, and he then stopped anyone else from entering. Later, all three of the men who had formerly entered, were found dead inside the tank.
Many people mistakenly think that a respirator or mask will protect them. Not so, if there is no oxygen, only a self contained oxygen supplied device, or self contained breathing apparatus (SCBA) can help.
While in the tail cone of your Seawind, always ensure that you have adequate ventilation. During the building process, while the tail cone is open, most of us place an air supply fan either in the front, blowing back through the tail cone, or a small fan in the water rudder area. The fan pulls or pushes fresh air through the tail section. After the tail is enclosed, just a fan may not be sufficient since there is no exit for the air. A way to circulate an ample supply of fresh air through the space is required.
There is an abundant amount of information about this topic on the web. If you are not familiar with the safety considerations about confined space it is suggested that you spend some time investigating. The following references, and some others are helpful: Wikipedia Confined Space and Confined Space Rescue Page.
Whatever you do, keep safety at the top of your list.
Safety is no accident.
Chris Doughtery from Planemakers working in the confined space of Seawind N66SW