Service Bulletins and Airworthiness Directives

RAM INFORMATION PAGE

RAM's RESPONSE TO THE PROPOSED EXHAUST A.D.

06 August 1999

Federal Aviation Administration
Central Region - Office of Regional Counsel
Attention: Rules Document No. 97-CE-67-AD
601 East 12th Street
Room 1558
Kansas City, Missouri 64106

Subject: Response to FAA Docket No. 97-CE-67-AD

Dear Sir or Madam:

RAM Aircraft Corporation (Repair Station No. VA1R551K), formed in 1976, has probably repaired and inspected more 300 and 400 Series aircraft than any other entity in the world. Due to the scope and detail of that extensive experience, RAM feels it may be best qualified to comment on the above referenced docket.

With respect to figure 1 of Docket No. 97-CE-67-AD, RAM would like to recommend the following revisions or deletions as applicable and duly noted below require that:

paragraph (b) all systems regardless of material, should have the complete system pressure tested*(see Attachment, RAM Maintenance Tip) each 100 hours TIS or each annual inspection; whichever comes first

paragraph (i) all new exhaust systems (parts) from slip joints aft to all turbocharger components, within 1600 hours of TIS or seven (7) years since new before inspection is required as required in paragraph (f)

paragraph (f) all serviceable exhaust parts REGARDLESS of material from slip joints aft to all turbocharger components be inspected within 500 hours TIS or two (2) years and returned to service by an approved repair station with serviceable tags denoting airworthiness (i.e. yellow tags)

paragraph (g) any V-Band clamp removed for component replacement would require a new clamp to be installed; all segmented clamps be replaced every 400 hours

paragraph (c) all overboard tailpipes be removed and visually inspected every one year or at annual inspection, whichever comes first

paragraph (h) disassemble and inspect exhaust slip joints and verify freedom of movement and pressure test every 100 hours and disassemble and inspect at each annual inspection

paragraph (i) delete entire paragraph - action required or allowed effectively negates the benefit of proposed AD

Conclusion: RAM has noted that well maintained aircraft that are in compliance with AD 75-23-08 have posed no problems. However, various discrepancies are obvious for those aircraft which not been properly inspected and maintained per AD 75-23-08. Furthermore, attempts to inspect and determine the wall thickness is not feasible. Additionally, RAM believes that there is no material advantage of inconel over stainless steel as a material of choice. In fact, there are no 100% inconel systems available. It should be noted that many maintenance facilities DO NOT have the appropriate experience, expertise or approved data to make these inspections properly resulting in aircraft being returned to service in an unacceptable condition.

Respectfully submitted,

RAM Aircraft Corporation
Cecil R. Padgett
President