FMTTI Minimum Sample Size Rules Explained

Why sample size matters

When someone asks us how many units they need to send for an FMTTI test, the honest answer is: it depends on what the machine costs and what category it falls into. Testing isn't done on a single hand-picked prototype. The institute draws its test units at random from a batch, and the minimum number of units in that batch is fixed by rule — not by how many the manufacturer feels like offering up.

This matters at the budgeting and planning stage, well before you fill in an application. If you're only set up to produce one or two demonstration units, you need to know early that the rule may call for five, ten, or even twenty.

The minimum sample size table

The governing rule sets minimum unit counts by price band for most machinery, with separate fixed counts for a few specific categories:

The logic runs the way you'd expect: cheaper, simpler machinery needs a bigger batch to draw a meaningful random sample from, while expensive, complex machinery like combine harvesters needs far fewer units simply because producing and supplying twenty of them for a test batch wouldn't be realistic.

How the random selection actually works

"Random sampling" isn't just a phrase in the rule — it's a real, documented step. For power tillers submitted for batch testing, for example, the unit tested has to be a genuine production model, selected at random from series production that's already been checked and cleared for delivery to distributors. Once it's selected, no further checks or adjustments are allowed before testing begins.

To make sure of that, key assemblies — the engine sump, fuel-injection pump and governor screw, cylinder head, clutch, gearbox, drive wheels and several others — are drilled, refitted and sealed with lead seals and twisted sealing wire, so nothing inside can be opened without breaking the seal. This is done with the manufacturer's representative present, and their signature is taken on the sealing form. The manufacturer then has to deliver the machine to the institute with every seal intact.

This same principle of random allocation runs through the wider testing process too: once your application and fee are through scrutiny, the institute allocates a test officer and test period through random sampling, rather than the manufacturer choosing the slot.

What this means for manufacturers

If you're planning a test, the sample size table is really a production-readiness check. A low-cost implement that needs twenty units for a ₹35,000-and-under batch is a bigger logistical commitment than it looks on paper, and it's worth lining up production well ahead of the application stage. For tractors, power tillers and combine harvesters the counts are lower, but the sealing and random-selection requirements mean the unit that turns up for test has to be a genuine, unmodified production item — not a unit specially prepared for the occasion.

We spend a lot of our time with manufacturers simply mapping their machine against the right price band and category before they apply, so the batch they're organising actually matches what the institute will ask for. Getting that number right early avoids a scramble — or a rejected application — later.

How we help

We guide manufacturers and dealers through exactly this kind of detail: confirming which sample-size band applies to your machine, what documentation needs to go in alongside it, and which institute will run the test. The testing itself — including the random selection and sealing — is always carried out by FMTTI's own engineers at the government institute; our role is to help you get to that point prepared.