Combustor Rumble can be a problem in engines that reverse the combustion gas flow prior toentering the 1st stage gas producer nozzle. Audible Combustor Rumble is created by 

unstable combustion, in addition to creating a significant increase in engine vibration during 

combustion instability. Unstable combustion occurs when the Air/Fuel ratio is less than 50 to 1. It is similar to the audible rumble heard when adjusting the air quantity on an oil furnace....

NOTE FROM UH1OPS
While we usually stick to maintenance articles on UH1OPS MAINTENANCE BLOGs, we support this product and after seeing the results, feel anyone operating a T53 engine should look into LubriBor, which we feel will save you money in the long run on components like fuel pumps and fuel controls.

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Because of low-sulfur requirements of today’s fuels, most engine OEMs have service bulletins or information letters detailing the need for a lubricity improver. This is a very economical way to reduce wear in fuel pumps and controls leading to lower overhaul costs in the future by reducing the number of parts needed during overhaul inspection.

If you're not familiar with lubricity improvers, this excerpt from ASTM Specification D...

Follow up to earlier Blog Article Combustor Rumble

Thanks to John Moore, we finally prevailed with Honeywell and they have agreed to putting a shim or shims in front of the deflector to control the gap between the deflector and combustor liner.  The desirable gap is 0.050 inch and not to exceed 0.080 inch.   It can be as low as 0.030 inch but fretting where the two surfaces contact will most likely occur.

The proper clearance between the 1st stage GP nozzle and 1st stage turbine has to be maintained. 

In addition, Honeywell has added the dimensional location of the 1-130-255-01 combustor liner mounting brackets but with a total tolerance of 0.030 inch between the mounting brackets.  It is recommended to hold the tolerance  to.005 inch.   Honeywell has also added the dimensional "he...

Compressor washes should be a routine procedure for those who maintain and operate gas turbine engines.
 

Albeit some engineers/A&P mechanics might consider compressor washes to be just another mundane task we must do “because it is written into our operations procedures” -  but let’s consider how compressor washes affect turbine engine performance and life cycles.

The T53 engine variant is a free power turbine engine that employs a five-stage axial and single-stage centrifugal compressor driven by a two-stage gas producer turbine. Dramatic engine performance degradation occurs with the ongoing accumulation of airborne contaminants within the compressor module thereby reducing the aerodynamic efficiency of the compressor blades that can result in deteriorating engine performance, u...

Reference cooled 1st GP Turbine Blade 1-100-362-06/08

Problem Statement

Air Technology Engines Inc. (ATE) has been communicating with Honeywell Engineering

since mid-2016 in reference to an observed deterioration/erosion of the cooled 1st GP

Blade Leading edge, outer, blade tip section. See attachment labeled GP Blade Tip

Erosion. This deterioration has been ATE observed in approximately 50% of the engines

received for a 2500-3000 hour inspection. The outer, leading edge, blade tip sections of

many/most blade...

Recommendation for Shipping in your Fuel & Governor for Repairs and Overhauls.

This a photo of a T1 sensing unit removed from a Fuel Control.

These should NEVER be removed from a Fuel Control they are calibrated together at the engine shop.

There are about five mentions in the PS magazines about this. Yet people still do it.

As you can see in the photo near the top  just to the left of a clamp there is a kink.

Now the unit is no good. And the Fuel Control it came from or the one they thought they were going to use it on will not work properly.

  Stay well and stay safe    Pete

I have known about this for years but thought this is information many may not know about the radio active materials in the T53 Engine.

The warnings used to be in the areas of the book where you were working.
With the changes they are harder to find.

When you see that white powder on the bottom of the inlet usually because the clamp is installed incorrectly that is the Magnesium / Thorium alloy, It should not be touched or inhaled. There are very special instructions for dealing with it.

When in doubt contact your engine shop. The exciter boxes were removed from active aircraft years ago, but I have seen engines that were put aside in cans or on early aircraft that came out of the system before the changeover that still have the radioactive ones.

As long as they are still sealed they a...

The TA-series fuel control system consists of two (2) components:
 

1. The Main Fuel Regulator (FCU) is a pump/control package in one. Series TA-7 for the -13 and

-703 and Series TA-10 for the -11 engines respectively.
 

2. The Power Turbine Governor (PTG). Series PTG-3.

Each component is procured separately and each is handled as an individual unit in all phases of

maintenance. During installation, however, the power turbine governor mounts on and operates in

conjunction with the main...

Everyone has installed something incorrectly at some point and had to learn the hard way and hopefully not the costly way.  Here are  a few items of notice we have seen again and again.  Something you may want to check on your own engine.  Because a simple mistake can turn into a costly one in the blink of an eye!~