mustanglover wrote:
51fixer wrote:
bdk wrote:
Does the NATA AMOC allow ultrasonic, or only dye penetrant?
The dye penetrant method is stated in the AD.
The NATA AMOC adds Eddy Current as a NDT method that can be used and changes the time interval on various areas around the angles.
The AD specifies the entire angle specified should be inspected every 200 hrs.
The NATA AMOC changes that to 1000 hrs except for the 1st 7" of the lower inboard angle on the removable stress door and the 1st 11" of the lower forward outboard angle on the outboard wing. This is on both sides, L and R, and this area remains at 200 hr intervals of inspection by the specified dye penetrant method or eddy current.
If we can ever get the LA-ACO (Aircraft Certification Office) and Washington, DC of their collective butts, we will PMA to produce all of those angles with a plan for an AMOC that will get rid of the repetitive inspections.
There is a lot of BS to this.
All situations are not the same when it comes to past usage and Environments that it has lived in.
Not all angles need to be changed and probably even inspected at the intervals of 200 hrs. That is why the NATA shared efforts to study the loads and strains imposed on the wing structure. Based on this data they determined the areas under the most load are the fwd 7" of the inboard angle on the stress door and the fwd 11" of the adjacent angle on the Outer wing. The AMOC from NATA requires the close inspection of those areas at the 200 hr times, not even the entire angle of those 2 pieces. This where the crack was on the doomed six that lost a wing.
Changing attach angles just because with no other reason is not cost effective and could induce some poor quality repair work. I've seen angles replaced that were done in a scary way. Almost as unsafe as the corroded piece that was replaced. NAA used 20+ steel screws on addition to rivets to attach the angle to the stress door. A 3/16" rivet is roughly 1/3 as strong in shear as an NAS 221 type screw. Yet I found a replaced angle with all rivets installed. All the screws had rivets in their place.
I'll admit that having new angles is a benefit if you need to change one. I've installed NOS ones from Lance. I just don't know if an AMOC requiring changing angles is the best answer unless you already need to make the change.