FAA concerned that unsafe conditions are not fully being addressed in ADs due to part rotation
FAA Advisory Circular (AC) 120-77 gives Operators option to rotate parts outside of Type Design allowances as minor alterations
At Airlines for America (A4A) meeting in 2017, Operators stated they prefer open ended ADs vs. not being allowed to rotate parts outside of Type Design allowances
Operators have recently been voicing concern over Boeing’s continued ability to support Service Requests, particularly 8100-9 component or rotable part repair approvals
Held recent three-way meeting with A4A on August 9thto come to a common understanding on Operator responsibility when rotating parts outside of Type Design allowances
Removable Structural Components (RSC) vs. Rotable Parts
Removable Structural Components
Structural Components routinely transferred between aircraft, resulting in a different utilization profile than the airframe the RSC is installed on
Rotable Parts
Same definition as above, only not limited to Structural Components. Line Replaceable Units (LRU) are a common form of non-structural Rotable Parts
Let’s cover shortly what is type design data?
Type Design includes, but is not limited to:
Engineering Drawings: Engineering Bill of Materials (EBoM) contains interchangeability provisions
Service Bulletins
Interchangeable Parts Drawings: Not to be confused with Illustrated Parts Catalog (IPC)
Service request responses: NOT Type Design data, unless rolled into Engineering Drawing (EBoM) or Interchangeable Parts Drawing provisions
Illustrated Parts Catalog (IPC)/STEPS:NOT Type Design Data, though typically reflective of Type Design
Rotable Parts -Example
747 Configuration
-1 flaptrack–L/N 1-500
-3 flaptrack–L/N 501-1000
-5 flaptrack–L/N 1001 and on
Two-way interchangeability between -1 and -3
Operators may have swapped out -5 for -1 flap tracks on A/Ps beyond L/N 1000 -would need approval from their local regulatory authority (e.g. AC 120-77)
Years later, -1 flap tracks found to prematurely crack
Boeing SB effectivity would cover 747s, L/N 1-1000
FAA AD applicability would be “All 747s, type certificated in any category”
Options presented by FAA at Airlines for America (A4A) Meeting:
Option 1: Rotation of parts limited to Type Design; FAA could then issue ADs with close-ended applicability
Option 2: FAA writes ADs applicable to all airplanes physically capable of receiving the affected part
Operators overwhelmingly chose Option 2, provided they could show AD compliance by part tracking records review
Boeing played more of an observer’s role at the meeting –all acknowledged that with Option 2, there exists a mis-match between Boeing SBs and FAA ADs
Note: Boeing and the FAA play more of a support role whichever option is chosen
SB Effectivity vs. IPC allowances
For any new safety-related service bulletins, Boeing would compare service bulletin effectivity against existing interchangeability provisions contained in there levant IPC
If IPC enables interchangeability outside of Type DesignData (should rarely occur):
Service bulletin effectivity may need to be expanded
IPC would be evaluated for appropriateness of additional interchangeability
Type Design Data may be updated accordingly
Boeing is looking to implement this on a trial basis
Note: In rare cases where IPC goes beyond Type Design effectivity, Boeing is exploring possibility of accounting for IPC allowances in Alert Service Bulletins
Acknowledgement of Part Rotability within SB Effectivity
For any new safety-related service bulletins, Boeing proposes to add a new Group 2 to capture airplanes where Operator may have rotated part outside of Type Design Data
Group 1 consists of airplanes:
Delivered with the unsafe part; or
Could have the unsafe part as allowed per Boeing Design interchangeability
Could include additional airplanes if allowed by IPC, should rarely occur (see prior slide)
Group 2: No service information provided, but Boeing acknowledges the possibility of rotation outside of Type Design Data. Include the following verbiage: This Service Bulletin does not authorize interchangeability of affected unsafe/discrepant parts on airplanes identified in Group 2. The retrofit instructions (including inspection, repair, modification) contained in this Service Bulletin are applicable to Group 1 airplanes only. Operators are encouraged to do a records review or maintenance check to identify unsafe/discrepant parts installed on airplanes in Group 2 and determine the necessary actions to address the unsafe condition. The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this Service Bulletin.
At prior STG, some Operators expressed concern with above proposal, that it may invalidate installation of parts outside of Type Design allowances.
8100-9 Repair Approvals
Operators have noted that Boeing now cites airplane effectivity for 8100-9rotablepart repair approvals which can be problematic
FAA ODA Guidance currently requires the listing of type design effectivity on8100-9 approvals
Operators believe the 8100-9 should provide design data approval as opposed to installation approval; hence, there should not be any installation restrictions included on the 8100-9
Boeing has discussed this with the FAA and they concur that the 8100-9serves as approval of design data evaluated against a particular configuration.
Boeing and the FAA also concur that if the Operator so chooses to subsequently rotate the repaired part outside of Type Design allowances, they assume full responsibility and must coordinate installation suitability with their local FAA office. This may be achieved by FAA oversight of Operator installation suitability processes.
Summary / Next Steps
Common understanding reached at recent A4A meeting:
a) Responsibility for rotation of parts outside of Type Design allowances falls upon the Operators; and
b) The local regulatory authority oversees part rotation via approval of Operator processes for appropriate part interchangeability as allowed by FAA AC 120-77
2. Boeing will continue to work with the FAA to explore alternate 8100-9 verbiage for repair support that is both compliant and does not restrict the customers’ ability to rotate parts outside of type design
3. Resume WTT efforts to address more long term goals
a) Bridge (if not eliminate) gap between SB effectivity and AD applicability for safety issues tied to rotables
b) Ensure rotables are being addressed consistently across the industry (i.e. other OEMs and regulatory authorities)
Picture made by Zack W