Here's the result of the technician's investigation. Interested in thoughts from this group as well. Thanks
1st Stage: Aqualung Micron
2nd Stage: Aqualung Micron
Intermediate Pressure at last Annual Service (9/26/13): 130 PSI
Mid Pressure Creep at last annual Service: None
2nd Stage Cracking Pressure at last annual Service: 1.2
Intermediate Pressure at diagnostic (3/25/14): 135
Mid Pressure Creep: None
2nd Stage Cracking pressure at beginning of Diagnostic: 1.2
Intermediate Pressure after dive (4/1/14): 135
Mid Pressure Creep after dive: None
2nd Stage Cracking pressure at end of diagnostic (post test dive): 1.4
Are adjustments within factory recommended settings? Yes
Findings:
Aqualung Micron Regulator set was received from the owner with complaints of a “Fluttering sound” at aprox. 70 FSW. Video was inconclusive as to whether the sound was emanating from the 1st or the 2nd stage. The regulator was attached to a high pressure air source (3000 psi) for a diagnostic check. The intermediate pressure and cracking pressure were consistent with those recorded during its previous annual service. Breathing on the primary second stage and the octopus failed to replicate the noise shown in the video. Consultation with Aqualung Technical Support resulted in no known reason for the identified sound. Aqualung recommended setting the Intermediate pressure to 135 PSI. It was suggested by the Aqualung Rep to take the regulator to 70FSW on a pony bottle and try to get it to make the same sound. The owner of the regulator gave permission to proceed with this testing. On 1 April 2014, the regulator was dove to a depth of aprox 80 FSW. Breathing on the regulator at this depth resulted in the sound emanating from the first stage on the first two inhalations. Subsequent inhalations failed to produce the sound. Breathing was alternated between fast, slow, shallow and deep, and at the same time manipulating the adjustment knob through the full range of operation. The regulator still did not produce this sound. The full range of testing was accomplished at intervals of every 10 feet from 80FSW to 20FSW. No sound was produced. Upon surfacing, the Intermediate pressure was checked, and then checked again after rinsing back at the maintenance facility. Both times, the IP remained unchanged. It is the determination of the service technician that the vibration noise is the result of harmonics on the mainspring during operation. Replacement of the spring could potentially stop this noise from continuing. Operation with the current spring should not pose a problem, with the exception of this noise occasionally being made.
