[BITList] Fwd: Over pressurization to fuel tanks during aerial refueling.

[John Feltham]

Begin forwarded message:


In-flight refuel Over pressurization


    Study the photos to see the extensive damage done.  “Wet wing”  
fuel tanks are mildly pressurized to check for leaks during PDM  
maintenance.  To avoid this type of damage, sensitive barometric  
equipment must be used to assure overpressurization does not occur.   
This is what happened when the mechanic inadvertently left the test  
plugs in the fuel tank ventilation system and the tanks were normally  
pressurized during flight.  Fortunately the wing did not disintegrate  
due to the Boeing failsafe design practice of 120% over maximum  
structural load factor.  The wing can be repaired, but it will be  
costly as KC-135 (B-707) parts have been out of production for about  
40 years.


EXECUTIVE SUMMARY                      AIRCRAFT ACCIDENT INVESTIGATION


              E-8C, T/N 93-0597                         AL UDEID AIR  
BASE, QATAR


On  13 March 2009, an R-8C JSTARS, tail number 93-0597, assigned to  
the 379
th  Air  Expeditionary  Wing,  experienced  a  near  catastrophic fuel  
tank
over-pressurization  during  aerial  refueling.   The  Mishap Aircraft  
(MA)
terminated  its mission and returned to Al Udeid Air Base, Qatar.  The  
crew
and  mission personnel evacuated the aircraft safely with no  
injuries.  The
mishap  resulted  in damage to the MA in the amount of $25 million  
dollars.
There was no damage to private property.


The  mishap occurred during operations in the Area of Responsibility  
(AOR).
The  Mishap  Crew  (MC) had begun aerial refueling (AR) with a KC-135,  
when
the  mishap core and personnel aboard heard and felt a loud bang  
throughout
the  midsection of the aircraft.  The MC suspended AR to evaluate the  
MA to
checkout their systems and evaluate the MA for any damage.  Finding  
nothing
apparently wrong, the MC re-latched to the tanker and attempted to  
continue
the  AR  when  another  series of loud noises and vibrations were  
heard and
felt  throughout  the  aircraft.   Personnel  aboard  the KC-135  
observed a
stream  of vapor and fuel streaming from the MA and alerted the MC.   
The MC
checked  for  damage through a rear window and observed fuel streaming  
from
at least two holes in the left wing, just inboard of the number two  
engine.
The  MC opted to terminate the mission and return to Al Udeid.   
Maintenance
personnel then examined the MA and found that the number two main fuel  
tank
had ruptured, causing extensive damage to the wing of the MA.


The  Accident  Investigation  Board  (AIB)  President  found,  by  
clear and
convincing   evidence,   that   the  mishap  was  caused  when  a   
civilian
subcontractor  employee  inadvertently  left  a  test plug in the fuel  
vent
system  of  the  MA  during recently completed Programmed Depot  
Maintenance
)PDM) performed on the MA.


Additionally, the AIB President found by substantial evidence three  
factors
which  contributed  to  the  mishap.  First, the PDM subcontractor  
employed
ineffective tool control measures.  Second, the PDM subcontractor  
failed to
follow  Technical  Order  (TO)  mandated procedures when employing the  
fuel
vent  test  plug  during PDM.  Third, due to the relatively short  
period of
time  between takeoff and AR, the MC did not have the opportunity to  
burn a
substantial  amount  of fuel from the number two fuel tank which could  
have
allowed  the  dive  "flapper" valve to open.  This explains why this  
mishap
did  not  occur  during AR's conducted between the time the MA left  
the PDM
facility and the time of the mishap.




ooroo

Bad typists of the word, untie.




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