AOPA Pilot Magazine - August 2011 - 22

LETTERS

Prime time for the Jabiru

enjoyed the article about the Jabiru J230-SP in June’s AOPA Pilot (“Prime Time for the Jabiru”), but am at a loss to understand the 104-degree-Fahrenheit operational limitation. Is there a degradation in airframe
strength when heated? Is the expansion rate of the dissimilar materials likely to cause delamination? Will this be a problem if the aircraft sits on the ramp when it is up to 120 degrees in the sun? I used to fly a Mooney out of Chico, California, where it often was more than 104 degrees F. Robert R. Corradini, AOPA 1562493 Palmetto Bay, Florida Al Marsh mentioned two rather large shortcomings, but did not expand on them—a recommended 1,000-hour top overhaul and the maximum air temperature of 104 degrees F for aircraft operations. At a price of $152,072, to not be able to utilize the airplane in temperatures easily found throughout the U.S. in the summertime, and to have to plan on a top overhaul at 1,000 hours, who do they expect to sell these aircraft to? The article gives the reader the idea that this is a great aircraft but glosses over these issues. Tim Bailey, AOPA 1170209 Clackamas, Oregon Al Marsh responds: The 104-degree F ambient air temperature limitation on the Jabiru composite airframe is actually the same as the 140-degree F limitation on many other brands of aircraft made of fiberglass or, in Jabiru’s case, a composite sandwich. Jabiru determines the critical internal temperature differently. Jabiru does not have an internal temperature probe so it uses NASA calculations. The top overhaul is because of running castiron rings in steel cylinders. Ring wear will take end-gap clearance beyond limits in about 1,200 hours; Jabiru picked 1,000 hours as the target for top overhaul. A soldier’s best friend I enjoyed the article “Cessna L–19 Bird Dog: A Soldier’s Best Friend” (June 2011 AOPA Pilot). However, I believe

there is one minor error in the article: The author states: “Cessna began work by mating the tail of a Cessna 195 and the wings of a Cessna 170B with a newly designed fuselage.” The part about the Cessna 195 tail may be correct (although I would like to know if there is any difference between the 170B’s and the L–19’s tail group), but I understand Cessna actually started with a 170A wing, added Fowler flaps, and three degrees of dihedral; they then used the L–19 configuration to produce the 170B. Although I have not been able to confirm this, it seems to make sense as the 170B did not enter production until 1952, well after the production and first flight of the L-19 (Cessna Model 305, December 14, 1949). Richard Wegener, AOPA 5695959 West Hartford, Connecticut Barry Schiff responds: It is possible you are right. I have six sources. Three state that the Bird Dog used Cessna 170 wings, while the others say 170B. I assumed that B was correct because the 170B wings were in development when the Bird Dog was cobbled together. I wouldn’t bet on it,

AOPA PILOT •

22 • AUGUST 2011

AOPA Pilot Magazine - August 2011

Table of Contents for the Digital Edition of AOPA Pilot Magazine - August 2011