Before I talk about the trip, I would like to give thanks to Mr. Dennis Cruz, who is the general manager of Freedom Air. Mr. Cruz has always supported our class and has given us an open pass whenever we need to use his facility for educational reasons.
In regards to the trip, I was able to show new and old students alike, how an aircraft looks when it is in the major maintenance phase. The Shorts 360 is in a Mid-Life Inspection, which means that a lot of its components were exposed for inspection.
Due to this condition, I was able to show the students the major structural members that would have been insidious under normal circumstances. Therefore, we looked at the stringers and the ribs of the main fuselage. I told my students that the holes were cut in the ribs to reduce the weight without compromising structural integrity.
Next we went into the cockpit where most of the avionics had been removed for calibration. While in the cockpit, students were allowed to move the control wheels laterally, thus simulating aileron control. Some students near the push-pull rods of the ailerons could actually observe the opposing movement that verified that the left and right ailerons worked in opposing directions. Students also observed: the rudder pedals, circuit-breakers, radio switches, elevator and aileron trim wheels, and steering/metering valve, which allows the aircraft to be steered while on the ground.
After we left the cockpit, we noticed the ballast (additional weight) in the forward cargo compartment. I explain to my Aeronautical Dolphins that extra weight was placed in the forward cargo compartment due to weight and balance. I continue with an example of a seesaw. I said that an aircraft has to be balanced, just like a seesaw. If you put too much weight in the front, then it will be too much weight on the nose and if you put too much weight in the aft section, then it will have too much weight on the tail. Therefore, the weight had to be installed in the forward cargo compartment to prevent the aircraft from resting on its tail.
After the weight and balance lesson, I brought their attention to the pitot tubes, which are located two feet underneath the pilot’s windows. I explained that pitot tubes are used to give the pilot his/her true airspeed of the aircraft by calculating the static and dynamic air pressure. Airspeed is critical during take-off, landing and even mid flight phase of operation. I brought to their attention, what happened to the Air-France aircraft that crashed in the Atlantic about four years ago. One hypothesis, is that the airspeed system malfunction, which gave the pilot an incorrect true airspeed. Unfortunately, the pilot was not going as fast as his indicators were showing. His actual speed was less than the velocity needed to maintain lift over the aircraft’s wings, which caused the plane stalled and eventually plunged into the Atlantic Ocean. Since, I am also the mathematics department chair at MHS, I made sure to inform the students that the pitot tubes are parallel to the relative wind and perpendicular to the vertical axis.
Finally, I gave a lesson about corrosion control. I added that the bare metal represented areas that corrosion had been removed. After cleaning the metal, then you have to prime and paint. Corrosion control is important in an island environment because salt is prevalent and salt is one of the primary substances that promote metal corrosion.
Currently, we are studying the history of aviation, and two key points that were mentioned on our trip was the manufacturer of the aircraft, which is the Shorts Corporation. My students were able to recognize that the Shorts Brothers were the first company to produce multiengine aircraft. And they were also able to recognize that W.S. Henson and John Stringfellow were the first to use ribs and a front and rear spars for wing construction
Our, next trip will be a visit on the Fly Guam 737-400 series aircraft.
The author teaches aviation at Marianas High School.
