Thanks Thanks:  0
Results 1 to 6 of 6

Thread: J4 questions

  1. #1
    a3holerman's Avatar
    Join Date
    Jul 2006
    Location
    Cape Cod
    Posts
    252
    Post Thanks / Like

    J4 questions

    Hi,
    I have been asked to give dual to a couple that just bought a 85 stroker powered, in very nice condition, J4.
    They keep it at the same field I keep my 185 and I said I'd be happy to get you both comfortable in it.
    Have done about 8 hours total with them and have a few questions.

    The wooden prop leading edge fabric near the tip came loose and the IA re glued it and it worked fine till now as the other blade is doing the same thing.
    He is going to fix that one today but it brings up the question of maybe they need a new prop. I am thinking metal but have been told the J4 is nose heavy, but cannot say I have noticed that in the flying we have done. The correct prop is also a question as to what is legal or quasilegal as the case might be. The owner says he hasn't found much info online perhaps due to the short production run.

    Wondering what the thoughts are on what to due about the prop?

    Thanks for any suggestions,

    Tom
    Tom
    Cape Cod

  2. #2

    Join Date
    Sep 2003
    Posts
    7,638
    Post Thanks / Like
    This happens to Sensenich wood props. Their type certificate specifies cotton, so they cannot use a more robust cloth.

    It is not legal to work on props without some special approval - you cannot even varnish them anymore.

    Since the statute of limitations is up, I can admit to fixing peeled fabric and varnishing props - I even re-tipped one once.
    New props are upwards of $3000 now - I personally think you will be just fine for decades with that prop, but go back to the sentence above for the official version.

  3. #3
    a3holerman's Avatar
    Join Date
    Jul 2006
    Location
    Cape Cod
    Posts
    252
    Post Thanks / Like
    Bob,

    Thank you for the advice. You are always the voice of reason.
    Tom
    Cape Cod

  4. #4
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,477
    Post Thanks / Like
    Quote Originally Posted by a3holerman View Post
    The correct prop is also a question as to what is legal or quasilegal as the case might be. The owner says he hasn't found much info online perhaps due to the short production run.

    Wondering what the thoughts are on what to due about the prop?

    Thanks for any suggestions,

    Tom
    Look at the TC A-703 on page 3, there are several different props which are approved:
    https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/9b8585992450b29a862572090072de81/$FILE/A-703.pdf

    I don't know where Bob got the idea that a mechanic can't replace the tip fabric and redo the varnish? That is one thing a mechanic is allowed to do on wood props.
    N1PA
    Likes CharlieN liked this post

  5. #5
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,477
    Post Thanks / Like
    More propeller information for the Piper J-4

    From A-703: Certification Basis Type Certificate No. 703 (CAR 4a)
    and: 101. Propeller - wood (fixed pitch)

    From CAR 4a:
    § 4a.597 Propellers. Propellers shall be of a type and design which has been certificated as airworthy in accordance with the requirements of Part 14 of this subchapter or shall have been approved as airworthy in accordance with previous regulations, except that wood propellers of a conventional type for use in light airplanes need not be certificated. In certain cases maximum engine bore limitations are also assigned to propellers. Propellers may be used on any engine provided that the certified power ratings, speed ratings, and bore of the engine are not in excess of the limitations of the propeller as certificated, and further provided that the vibration characteristics of the combination are satisfactory to the Administrator.
    Last edited by skywagon8a; 10-03-2021 at 09:42 AM.
    N1PA
    Likes wireweinie liked this post

  6. #6
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,477
    Post Thanks / Like
    Upon further inspection, it appears only one propeller is approved with the C-85 engine.
    *301. Engines, Continental
    (4) C-85-12 (J4A with Item 3 propeller)
    3. Propeller - Sensenich 74-FK-49 or any other fixed pitch +11 lbs. (-50) wood propeller which is eligible for the engine power and speed and which meets the following limits: Diameter: Not over 74 in., not under 72.5 in. Static r.p.m. at maximum permissible throttle setting: Not over 2175, not under 2075. No additional tolerance permitted. Eligible with Item 301(b)(4) only.

    Tom, Nothing of what you said would indicate the current prop needs replacing.
    N1PA

Similar Threads

  1. ADS-B and other questions.
    By Tennessee in forum Member to Member
    Replies: 52
    Last Post: 05-02-2018, 11:19 AM
  2. Replies: 4
    Last Post: 08-12-2014, 06:02 PM
  3. 3 questions
    By James L. Smith in forum Cafe Supercub
    Replies: 6
    Last Post: 11-22-2006, 09:03 AM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •