# Presentation: 917056

## Propeller Change

- Fully define alteration:
- Aviat A-1B ‘Husky’, TCDS # A22NM, Part 23 dated February 1, 1965 as amended by 23-1 thru 23-31 (Normal Category) and FAR 36 amended thru 36-12,. FAR 21 amended thru 21-57. )
- Modification to Propeller, Spinner, Engine Crank, governor, and prop control cable, Flight Manual Operating Limitations.
- Specifics;
- Increase from 80” to 82” inch prop, no reduction in RPM.
- Change from constant speed to fixed pitch.
- Must modify crank to plug orifices (search find AD’s on crank)
- Remove governor and install plate.
- Remove Placard Limitation
- Add FMS for Limitation, Normal, Emergency Ops, Etc...

## Major/Minor Design Change Issues

- Is it a Major Change in Type Design?
- Is this change appreciable?
- Yes; the prop governor is removed, the control is no longer in the cockpit.  No Manifold Pressure gauge on panel.  This is an appreciable change at Product level.  Effect on operational characteristics (Take-off performance)
- It could also be an Acoustical change per FAR 21.93
- Was aircraft registered and flown prior to January 1, 1955
- Is the aircraft being altered as part of a float mod (temporary)
- Under some instances Float planes and ski planes may be exempt from Noise rules.
- Is there a change in the dB level output of the aircraft.
- Tip Mach Number
- Performance
- Weight

- Directorate may flag this as a significant project.

## Certification Issues

- Changes that _detrimentally_ affect takeoff performance are probably Major (STC).
- Is there a change in engine operating limits, like RPM or avoid continuous operation limitations.
- Placard required**: "AVOID CONTINUOUS OPERATIONS BETWEEN 2000-2250 RPM"**	(On original Prop instl.)
- If there is a change in the basic engine configuration outside of previously approved data?
- Engine and Propeller Combination should be certified on a previous installation.

- THIS SPECIFIC MODIFICATION SHOULD BE A
- _STC_

## STC(Points of Discussion)

- Level of Documentation (photos vs. drawings)
- Multiple STC’s will require production quality drawings
- STC Application;
- Send to the Geographical  ACO (FAA Form 8130-12)
- Anchorage ACO in the case of Juneau applicants
- Cover Letter submitting application
- Draft Project Specific Certification Plan (PSCP)
- Compliance Checklist.

- STC*(Points of Discussion)*

## STC(Points of Discussion)

- Define project (Make/Model/TCDS/Change description)
- Serial No. if one-time
- Use of Designees
- Compliance Checklist
- Multiple STCs will require production quality drawings
- One-time is okay with photos
- Schedule and responsibilities
- Compliance Checklist
- Larger more in-depth version of checklist provided.
- Define method of compliance with regulations (Analysis, Drawings, Tests...)

- STC*(Points of Discussion)*

## STC(Points of Discussion)

- Performance
- Noise
- Flutter (test VD)
- Cockpit layout (removal of manifold gauge)
- Obtain Type Inspection Authorization.
- ICA
- Would need to address the AD on the crank.
- Alternate Method of Compliance (AMOC)
- Needs approval by AD issuing ACO
- Flight Manual Supplement (needs ACO Approval)
- Change in Limitations.
- Change cockpit layout.
- Change in  Normal / Emergency procedures.

- STC*(Points of Discussion)*

## Acoustical Issues(Points of Discussion)

- If not, a Noise Test needs to be proposed and scheduled.  Usually a Noise DER is required  (In Alaska there are times of the year that noise tests are difficult due to the cold weather)
- If  performance is affected, a flight test will be required
- The flutter characteristics can be checked by testing to Vd or by a flutter analysis and a test to redline (Vne).
- If the prop is longer, we need to check ground clearance. (two conditions)
- If the Propeller DER imposes a limitation on certain RPM ranges those limits will have to be imposed using placards in the cockpit.

- Acoustical Issues*(Points of Discussion)*

## QUESTION 

**&**
**ANSWER**
**OR**
**OPEN DISCUSSION**