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Flap pulley bracket cracks

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cpayne(at)joimail.com
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Posted: Tue Mar 21, 2006 2:59 pm Post subject: Flap pulley bracket cracks

Just finished with the General Condition inspection for my CJ. Other than the usual wear and service items, one "find" stood out: small cracks in the right and left outboard Flap pulley brackets. This is where the cable turns 90 degrees to the flap sides. Stop drilling was the immediate measure but doublers will be in the works.

  

 Cause? Well, this is the New Age where nobody is ever responsible for their own actions...sooo, it must be from the childhood strain of being the oldest of 4 brothers with a widowed mom.... that tramatic experience caused me to deploy the flaps before the aircraft bled off enough speed. Must be angst from my childhood. I'll call Mom this weekend and complain. Or,  maybe I don't know what the Max Flap down speed is for the CJ. Anyone have a speed number?

  

 Craig Payne

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ByronMFox(at)aol.com
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Posted: Tue Mar 21, 2006 3:12 pm Post subject: Flap pulley bracket cracks

In a message dated 3/21/06 3:00:04 PM, cpayne(at)joimail.com writes:

 

 

  	  Quote: 	
		  Max Flap down speed is for the CJ. Anyone have a speed number?

 	


 

 I've been using 100kts, Craig, but would like to know if I'm too fast. ...Blitz

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brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Tue Mar 21, 2006 4:01 pm Post subject: Flap pulley bracket cracks

Craig Payne wrote:



 	  Quote: 	
		   complain. Or,  maybe I don't know what the Max Flap down speed is for 

 the CJ. Anyone have a speed number?


	


Speeds



Vs0 (stall gear, flaps down) 59 Kts (108 Kph)



Vs1 (stall clean) 61 Kts (112 Kph)



Vfe (max flap extension speed) 108 Kts (198 Kph)



Vlo (gear down speed) 130 Kts (240 Kph)



Va (maneuvering speed) 149 Kts (275 Kph)



Vd (maximum dive speed) 201 Kts (370 Kph)

Brian

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_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

wlannon(at)cablerocket.co
Guest

Posted: Tue Mar 21, 2006 7:42 pm Post subject: Flap pulley bracket cracks

Craig;

  

 Are the cracks located in the flap where the cable  attaches or at the pulley brackets on the wing trailing edge ribs?

  

 Neither one is an area that I would expect  damage from too high a flap down speed (but who knows). 

 With regard to the flap down limit speed  there is some difference of opinion. I recommend specific flap and gear  limits to all who order cockpit placards. These limits are based on a structural  evaluation (including gear doors and attachment) of the CJ in comparison to the  Harvard (T6), Beech T34 and Piper Comanche. Only the Harvard flap structure is  comparable enough for a reasonable evaluation of the flap limit.

  

 Those numbers are; Flap - 90 Kts, Gear - 110  Kts.

  

 The PLAAF does not give specific gear & flap limits in  the Pilots Flight Manual BUT they do specify a maximum speed in the circuit of  170 Kph (92Kts)

  

 Many of the CJ owners in the US believe the limits are 108  and 130 Kts respectively. 

 I understand these numbers came from Yakkity-Yaks but  don't know for sure. Interestingly these are the limits for the AT6 series of  aircraft. IMHO they do not apply to the CJ. Without boring everyone with a lot  of detail the CJ flap speed is limited by the single point of actuation compared  to a multiple point T6 system. The gear speed is limited by the large gear doors  with somewhat questionable attachment.

  

 Walt

  

 [quote]   ---

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wlannon(at)cablerocket.co
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Posted: Tue Mar 21, 2006 7:42 pm Post subject: Flap pulley bracket cracks

---

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wlannon(at)cablerocket.co
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Posted: Tue Mar 21, 2006 8:03 pm Post subject: Flap pulley bracket cracks

Hi Brian;



Re: Flap and gear limits, see comments in previous answer to Craig's post.



Where did you find the Va? The only numbers I have noted  seem to be more 

like max. structural cruise than maneuvering speeds.



Vd should read Vne. Vd is maximum demonstrated dive speed at, Vne is 90% Vd.

Interesting that the CJ6 Vne is 350 Kph while the CJ6A is 370 Kph. Duh!! 

Does that mean they were able to demonstrate a higher Vd with the extra 25 

HP ????????

Or does that mean the aircraft gets stronger with more HP????????



Cheers;

Walt



 	  Quote: 	
		   Speeds



 Vs0 (stall gear, flaps down) 59 Kts (108 Kph)



 Vs1 (stall clean) 61 Kts (112 Kph)



 Vfe (max flap extension speed) 108 Kts (198 Kph)



 Vlo (gear down speed) 130 Kts (240 Kph)



 Va (maneuvering speed) 149 Kts (275 Kph)



 Vd (maximum dive speed) 201 Kts (370 Kph)

 Brian



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brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Tue Mar 21, 2006 11:14 pm Post subject: Flap pulley bracket cracks

Walter Lannon wrote:

 	  Quote: 	

 Hi Brian;

 Re: Flap and gear limits, see comments in previous answer to Craig's post.

Good info, thanks.

 	  Quote: 	
		   Where did you find the Va? The only numbers I have noted  seem to be 

 more like max. structural cruise than maneuvering speeds.

Va is actually easy to calculate. You want to know airspeed where the 

wing will stall right when you reach maximum load factor so you take the 

stall speed at 1G and multiply by the square root of the maximum load 

factor.

If the stall speed is 61 kts and the max airframe load is 6g,

    61*sqrt(6) = 149.4 kts.

 	  Quote: 	
		   Vd should read Vne. Vd is maximum demonstrated dive speed at, Vne is 90% 

 Vd.

 Interesting that the CJ6 Vne is 350 Kph while the CJ6A is 370 Kph. Duh!! 

 Does that mean they were able to demonstrate a higher Vd with the extra 

 25 HP ????????

 Or does that mean the aircraft gets stronger with more HP????????

This was a big question some years back. I agree that the number I 

listed as Vd is probably more like what we call Vne here in the US. 

Still, the Chinese call it Vd and given that it wasn't clear how they 

classified it, I just left the name alone. Bushi Cheng confirmed that it 

is safe to operate the aircraft at Vd. (And I know that the airplane 

will hang together just fine at 231 kts.) As I recall he said something 

about it being the maximum speed they demonstrated, not necessarily the 

maximum safe speed. But that could just be the marbles rattling in my 

head talking.

And you are right: the numbers for Vfe and Vlo came from Yakity-Yaks. 

Unfortunately there just weren't any other numbers. But I am not married 

to them. We discovered that there were a couple of things that came out 

of Yakity-Yaks that weren't quite kosher. I guess there are a number of 

airplanes that are flying with exactly the same W&B data even tho' the 

airplanes are configured differently. So these numbers could be 

questionable as well. Still the airplane seems to hold up OK using the 

numbers I gave for Vfe and Vlo.

 	  Quote: 	

 Cheers;

 Walt

> Speeds

>

> Vs0 (stall gear, flaps down) 59 Kts (108 Kph)

>

> Vs1 (stall clean) 61 Kts (112 Kph)

>

> Vfe (max flap extension speed) 108 Kts (198 Kph)

>

> Vlo (gear down speed) 130 Kts (240 Kph)

>

> Va (maneuvering speed) 149 Kts (275 Kph)

>

> Vd (maximum dive speed) 201 Kts (370 Kph)

> Brian

>

> http://www.matronics.com/Navigator?Yak-List

>

>

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-- 

Brian Lloyd                         361 Catterline Way

brian-yak at lloyd dot com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .

- Antoine de Saint-Exupery

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