Broken AirplaneS

Given the demands made of carrier aircraft, it's not unusual that they stop working to some degree.  As the Reconnaissance Attack Navigator in the back seat of the RA-5C,  I was directly concerned with  the various mission systems:  navigation, bombing, and and reconnaissance equipment.  When working properly, the A-5 was a wonder.  Its inertial navigation system get us a continuous readout of position and attitude, independent of external signals and immune to jamming.  Trouble was, it it was unreliable, and there were usually  no warning about its growing inaccuracy.

Still, the failure of the back-seat equipment would degrade mission performance.  Failure of the airframe could be a lot more serious.  The RA-5C used a high (3000 psi) pressure hydraulic system to control aerodynamic surfaces on the aircraft.  Failure of hydraulics would almost always mean loss of the aircraft,  So, the hydraulic systems were redundant.  Hydraulic system failures were all too common, but the redundancy generally allowed for a safe landing.    

Hard landings often led to structural issues (see photos nearby).  The RA-5C was about 10,000 pounds heavier than the A-5A version, yet the landing gear was not beefed up. So these types of accidents were all too commoon. Fortunately, there was generally no loss of life.

Engine failures were not unknown.  The General Electric J-79 turbojet was a high performance engine also used in the F-4 Phantom II and numerous other high performance aircraft.  It featured variable stator vanes for higher performance and variable geometry intakeand exhaust ducts for the same reason.  Failureof any  of these subsystems at a minimum meant degraded performance, and possibily complete engine loss.  

Structure of the aircraft was also sometimes an issue as well.  The RA-5C had a reputation for mysterious accidents, e.g.,  670817- RA-5C lost to unknown causes- both crewmembers KIA .  Stuctural  failure of load bearing parts of of the aircraft almost always leads to very bad consequences.  

Stressed skin construction is used in  most high performance aircraft, along with  other load bearing members such as wing struts.  Failure of the latter is fortunately very  rare, and presumably noticeable right away.  What about failure of the stressed skin construction.  Harder to see since it could be anywhere on the aircraft.

In early  1968,  I was still Aircraft Line Division Officer, responsible for getting the aircraft ready for flight and securing them afterward, along with minor maintenance.  I spent much of my my non-flying time on the flight deck keeping an eye on things.

One of the pre-flight duties was an aircraft walkaround.  This was to spot any visible issues, such as hydraulic leaks, tire pressure, and the like.   On this particular flight, I was following up the plane captain's inspection with a casual one of my own.  While walking down the right side of the aircraft, I noticed something peculiar on the fuselage under the wing.  There was a crack  in the skin, about a foot long!  Since the skin is a load bearing compoentent, any compromise is very serious indeed!  It's entirely possible that the airframe would have catastrophically  failed when subjected to inflight loads.  

The skin tear was in an area generally not subject to pre-flight inspection.  Could cracks of this nature been the  the source of some of the mysterious RA-5C losses?