An ADR is used to report critical, major, or minor discrepancies. Definitions of critical, major, and minor deficiencies  are  as  follows: A  critical  defect  constitutes  hazardous  or  unsafe condition (or as determined by experience and judgement   could   conceivably   become hazardous and unsafe), thus making an aircraft unsafe  for  flight  or  endangering  operating personnel. A major defect is a defect that could result in failure or materially reduce usability of the unit for its intended purpose. A minor defect is a defect that is not likely to materially  reduce  usability  of  the  unit  or  product for  its  intended  purpose  or  departs  from established   standards. Submit the required ADR within 5 working days after  completion  of  an  acceptance  flight.  A supplemental ADR, if any, must be submitted within 30 days of completion of the acceptance check flight. Submit a negative response if no discrepancies are found. State “No Discrepancies Noted, Reply Not Required” in Block 22 of Standard Form 368. Use the preaddressed envelopes that should be in the manila envelope  in  each  aircraft  logbook.  Refer  to OPNAVINST 4790.2 for more information on ADRs. ENGINEERING  INVESTIGATION  (EI) An engineering investigation (EI) provides an investigative process to determine cause of an aircraft mishap,   lightening   strike,   weapon   system   and equipment failure, or fleet-wide material problem. An EI is submitted in support of the investigation. An EI should   be   submitted   whenever   the   following circumstances  exist: Safety is involved. This includes an EI request that is prepared in conjunction with an aircraft mishap and an HMR when an unsafe condition exists Additional technical or engineering information is  required  to  complete  an  aircraft  mishap investigation. Aircraft readiness is seriously impaired due to poor material reliability. A component is rejected through the Naval Oil Analysis  Program  (NOAP)  after  all  authorized repairs are attempted. An  environmental  issue  requires  a  change  in material or process that is in conflict with a material  or  process  that  is  specified  in  an existing publication or TD. Higher  authority  directs  that  the  investigation  be conducted. Unless combined with an HMR, an EI request should be submitted by routine priority message within 5 working days after discovery of the deficiency. A combined  report  follows  HMR  reporting  criteria.  Refer to OPNAVINST 4790.2 for handling and preparation of  EI  material. TECHNICAL PUBLICATION DEFICIENCY REPORT (TPDR) A technical publication deficiency report (TPDR) is a simplified method for reporting a safety hazard or routine  deficiency  in  a  technical  publication.  Technical publications where TPDRs can apply include MRCs, checklists, WUC manuals, shop process cards, MIMs, weapon loading manuals, stores loading manuals, conventional  weapon  checklists,  nuclear  weapon checklists, stores reliability cards, IPB listings, TDs, and technical manuals. The TPDR is the NAMDRP report that the CTPL will be most concerned with since the CTPL librarian submits and monitors this report. Some routine deficiencies may not require issuance of a change   for   immediate   corrective   action.   Other deficiencies are critical and may, if not corrected, cause serious injury or death to personnel, loss of equipment, or damage to personal or government property. Some of   the   more   common   deficiencies   include   the following: Incorrect  operating  or  troubleshooting  proce- dures Incorrect or missing part numbers Format errors affecting maintenance Missing details Incorrect artwork NOTE:  A   deficiency   or   routine   change recommendation in a Naval Air Training and Operating Procedures Standardization (NATOPS) manual or other tactical manual should be reported under the NATOPS/Tactical  Manual  Deficiency  Reporting Program by submitting a NATOPS/Tactical Change Recommendation  Form,  OPNAV  Form  3710/6. Instructions for processing OPNAV Form 3710/6 are 3-28