Gross Weight Increase with Glass Cockpit

[RoundTwo]

If a plane is eligible for the GW increase but has no analog airspeed indicator left to be painted or replaced, is it just a matter of adding the AFM supplement to the POH and checking rudder balance? I’m not clear what checking rudder balance has to do with a GW increase, so maybe someone can explain that as well.

R2

[A64Pilot]

I can’t quote chapt and verse but there are several calculations that are made if you increase gross weight that may affect operating airspeeds etc. Presumably the rudder is the most critical for flutter on a Mooney, and it’s balance would need to be checked to validate it was within limits.

When we did a gross weight increase on the Thrush, it was ailerons, and we had to narrow the acceptable range of allowable limits, which made them a different part number.

I do not know that’s the deal on a Mooney but suspect it is.

[toto]

2 hours ago, A64Pilot said:

I can’t quote chapt and verse but there are several calculations that are made if you increase gross weight that may affect operating airspeeds etc. Presumably the rudder is the most critical for flutter on a Mooney, and it’s balance would need to be checked to validate it was within limits.

When we did a gross weight increase on the Thrush, it was ailerons, and we had to narrow the acceptable range of allowable limits, which made them a different part number.

I do not know that’s the deal on a Mooney but suspect it is.

That’s my understanding of the Mooney service letter as well. 

The instructions actually say nothing at all about remarking the airspeed indicator — they tell you to purchase a kit from Mooney that includes a new ASI with the correct markings, and then install the new AFMS after having the rudder balance test. 

Most of the people who are logging compliance with the service bulletin are doing it after remarking the ASI (in part, I suspect, because you can’t buy a new ASI kit from Mooney). But the SL doesn’t cover that action. Reprogramming the airspeed indications in a glass panel ASI is essentially the same thing as remarking the mechanical ASI, and neither is covered by the SL.

Since this isn’t an STC, but an update to the original type certificate, and the SB+SL itself is not mandatory under Part 91, there may be significant latitude in logging compliance. I’d be interested to know A64’s insights here. 

SL92-1_SN24_1686-2999.pdf

[A64Pilot]

In all honesty I believe you have to purchase the kit to be perfectly legal. That’s my opinion, largely because some kits are very extensive and pretty difficult or impossible to perfectly duplicate, but others will have different opinions of course.

Back in the day Ayres sold a kit to convert piston Ag planes to Turbine, the kit included a parts list of course, included everything but the engine and prop.

Ayers and Thrush have fielded dozens of “Custom kits” Brakes, tires, you name it.

https://thrushaircraft.com/support/technical-publications/Custom Kits/ckag20 POWER PLANT CONVERSION-PISTON TO TURBINE.pdf

Many, many aircraft were converted and the paperwork said the kit had been installed, but in fact no kit had been bought.

So in my opinion to comply with the letter of the law, if you’re installing a kit and signing it off as xx kit installed, you have to buy a kit. But there are many cases of parts being sourced elsewhere and a kit signed off.

 

[kortopates]

It’s a standard practice to remark an airspeed indicator. The same thing is done going from the 252 to Encore conversion. I’ve been involved in both the J and K conversions. Maybe years ago it was cheaper to install a new IAS indicator, but i doubt it. These days re-configuring a digital IAS v-speeds is easiest.


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[RoundTwo]

56 minutes ago, kortopates said:

It’s a standard practice to remark an airspeed indicator. The same thing is done going from the 252 to Encore conversion. I’ve been involved in both the J and K conversions. Maybe years ago it was cheaper to install a new IAS indicator, but i doubt it. These days re-configuring a digital IAS v-speeds is easiest.


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So, this got cheaper if there is no analog gauge anymore. The SB has the AFM supplement, so I guess all you have to do is add the AFM supplement to the POH and check/rebalance the rudder and sign it off. Does any of that sound incorrect?

R2

[1980Mooney]

12 minutes ago, RoundTwo said:

So, this got cheaper if there is no analog gauge anymore. The SB has the AFM supplement, so I guess all you have to do is add the AFM supplement to the POH and check/rebalance the rudder and sign it off. Does any of that sound incorrect?

R2

You need to program your “glass” ASI display to reflect the changes in increased stall speed at the new higher MGW for the white arc  and green arc. That is a primary flight instrument and your plane is not airworthy without making the changes.  Sounds pretty simple - easier and cheaper than changing an analog gauge. 

Edited February 19, 2023 by 1980Mooney

[EricJ]

Bottom line is that the ASI has to reflect what is shown in the limitations section of the POH/AFM, properly reflecting any modifications due to STC or 337.

Some old school AIs are fine with just the redline being correct, but I wouldn't count on that.

[1980Mooney]

On 2/18/2023 at 2:24 PM, toto said:

Most of the people who are logging compliance with the service bulletin are doing it after remarking the ASI (in part, I suspect, because you can’t buy a new ASI kit from Mooney). But the SL doesn’t cover that action. Reprogramming the airspeed indications in a glass panel ASI is essentially the same thing as remarking the mechanical ASI, and neither is covered by the SL.

Since this isn’t an STC, but an update to the original type certificate, and the SB+SL itself is not mandatory under Part 91, there may be significant latitude in logging compliance. 

 

9 hours ago, RoundTwo said:

So, this got cheaper if there is no analog gauge anymore. The SB has the AFM supplement, so I guess all you have to do is add the AFM supplement to the POH and check/rebalance the rudder and sign it off. Does any of that sound incorrect?

The more I look at the regs the more I agree with you. There used to be Airworthiness Standard § 23.1545 "Airspeed indicator." but it is gone.  It has been replaced with § 23.2610 "Instrument markings, control markings, and placards.".  It is very general with latitude that by default delegates the decision to the manufacturer or the IA. - "display in a conspicuous manner any placard and instrument marking necessary for operation"

 § 23.1545 Airspeed indicator. (Has been replaced)
(a) Each airspeed indicator must be marked as specified in paragraph (b) of this section, with the marks located at the corresponding indicated airspeeds. 
(b) The following markings must be made: 
(1) For the never-exceed speed VNE, a radial red line. 
(2) For the caution range, a yellow arc extending from the red line specified in paragraph (b)(1) of this section to the upper limit of the green arc specified in paragraph (b)(3) of this section. 
(3) For the normal operating range, a green arc with the lower limit at VS1with maximum weight and with landing gear and wing flaps retracted, and the upper limit at the maximum structural cruising speed VNO established under §23.1505(b). 
(4) For the flap operating range, a white arc with the lower limit at VS0 at the maximum weight, and the upper limit at the flaps-extended speed VFE established under §23.1511. 

§ 23.2610 Instrument markings, control markings, and placards. (Current regulation)

(a) Each airplane must display in a conspicuous manner any placard and instrument marking necessary for operation. 

(b) The design must clearly indicate the function of each cockpit control, other than primary flight controls. 

(c) The applicant must include instrument marking and placard information in the Airplane Flight Manual.

Edited February 20, 2023 by 1980Mooney

[EricJ]

10 hours ago, 1980Mooney said:

 

The more I look at the regs the more I agree with you. There used to be Airworthiness Standard § 23.1545 "Airspeed indicator." but it is gone.  It has been replaced with § 23.2610 "Instrument markings, control markings, and placards.".  It is very general with latitude that by default delegates the decision to the manufacturer or the IA. - "display in a conspicuous manner any placard and instrument marking necessary for operation"

 § 23.1545 Airspeed indicator. (Has been replaced)
(a) Each airspeed indicator must be marked as specified in paragraph (b) of this section, with the marks located at the corresponding indicated airspeeds. 
(b) The following markings must be made: 
(1) For the never-exceed speed VNE, a radial red line. 
(2) For the caution range, a yellow arc extending from the red line specified in paragraph (b)(1) of this section to the upper limit of the green arc specified in paragraph (b)(3) of this section. 
(3) For the normal operating range, a green arc with the lower limit at VS1with maximum weight and with landing gear and wing flaps retracted, and the upper limit at the maximum structural cruising speed VNO established under §23.1505(b). 
(4) For the flap operating range, a white arc with the lower limit at VS0 at the maximum weight, and the upper limit at the flaps-extended speed VFE established under §23.1511. 

§ 23.2610 Instrument markings, control markings, and placards. (Current regulation)

(a) Each airplane must display in a conspicuous manner any placard and instrument marking necessary for operation. 

(b) The design must clearly indicate the function of each cockpit control, other than primary flight controls. 

(c) The applicant must include instrument marking and placard information in the Airplane Flight Manual.

Mooneys aren't Part 23 airplanes, though, since they were certificated under CAR 3.

[mooniac15u]

5 minutes ago, EricJ said:

Mooneys aren't Part 23 airplanes, though, since they were certificated under CAR 3.

Starting with the J they were certificated under a mix of CAR3 and Part 23.  You have to check the type certificate to determine which paragraphs from Part 23 are applicable for each model.  The amount of Part 23 used increases with the more recent models.

[1980Mooney]

1 hour ago, EricJ said:

Mooneys aren't Part 23 airplanes, though, since they were certificated under CAR 3.

Good point. Under CAR 3.757 the White and Green Arc’s or marking’s are required to be airworthy.  So - no latitude - you must adjust your new higher Vs0 and Vs1 at MGW on your glass ASI  

[A64Pilot]

7 hours ago, mooniac15u said:

Starting with the J they were certificated under a mix of CAR3 and Part 23.  You have to check the type certificate to determine which paragraphs from Part 23 are applicable for each model.  The amount of Part 23 used increases with the more recent models.

That’s real common, the FAA can and will drag you into part 23 if they can show that doing so will “materially improve safety” I know because I had to fight them and my Engineer who wanted to certify the aircraft as fully FAR 23, I guess as a feather in his hat.

So it’s real common for aircraft that went into manufacture after 23 was adopted to have a mix of 23 and CAR 3, which of course complicates things because a mechanic is supposed to know what’s part 23 and what isn’t, good luck.